Buying Plumbing

[emissary]

So I'm starting to think about the lego... err... PVC pieces I'm going to need for my overflows, returns, etc. My plumbing job on my 75G was horrible and relied entirely on what I saw at home depot... I think this is why it ended up horrible.

 

Anyway, I'm looking for a place to buy *stuff* both schedule 40 and 80 (color reasons). Ideally a place where I can touch and feel my way through the plumbing design. Anyone know of anything in the Vienna/Fairfax/Falls Church or neighboring area that would be good? I've heard lowes has better plumbing supply than HD.

 

I could try to order it all online, but I'm not sure what prices are reasonable. I mean... marine depot sells ball valves for twenty two dollars a piece (1.5"). This seems excessive to me. Moreover I'm not sure I'll order the right pieces.

 

Thoughts?

[GaryL]

fischer's ace hardware in springfield is very good, second by pitkins in woodbridge. also lowes here in woodbridge has a good plumbing section

[Guest Keyoke]

So I'm starting to think about the lego... err... PVC pieces I'm going to need for my overflows, returns, etc.  My plumbing job on my 75G was horrible and relied entirely on what I saw at home depot... I think this is why it ended up horrible.

 

Anyway, I'm looking for a place to buy *stuff* both schedule 40 and 80 (color reasons).  Ideally a place where I can touch and feel my way through the plumbing design.  Anyone know of anything in the Vienna/Fairfax/Falls Church or neighboring area that would be good?  I've heard lowes has better plumbing supply than HD.

 

I could try to order it all online, but I'm not sure what prices are reasonable.  I mean... marine depot sells ball valves for twenty two dollars a piece (1.5").  This seems excessive to me.  Moreover I'm not sure I'll order the right pieces.

 

Thoughts?

32854[/snapback]

 

Yeah. I like Lowes myself compared to HD...

 

Those ball valves are costly.. Lowes has "union" ball vales, which are _really_ nice, and _really_ expensive. There are about 3 types - straight ball valves, Ball valves with a union on 1 side, and ball valves with unions on both sides. At lowes a 2" union on each side ball valve cost me about $32. Good thing I only needed one of 'em. The 3/4" ones I use on returns were about $10 if I recall correctly...

 

Also, you'll get a better deal if you buy contractors packs on things like ELL's, couplings, etc. Anything your going to need a lot of. Packs of 10 are about $2 cheaper than buying 10 street ELLs.

 

nice thing about lowes, tho the cashiers hate you when you do this - buy about twice what you think you'll need. You can always take it back when your done. Poor lady last time I did that had to re-scan in about 20 items.. Got my $8.00 back tho.

[fishface]

For specialty items and probably a lot of basic items, there's Booz plumbing right at Nutley and 123 in Vienna. I ordered a pressure reducer some months ago. I'd call ahead if you're looking for bulkheads or other Marine items. I never looked at pricing for fittings, but it's close by. Except for valves, you probably won't go broke.

 

You can get bulckheads at The Reeftank, or the Sterling Home Depot- but they are no longer stocking marine fitings, so it's whatever is left on the shelve to pick at.

 

Lowes usually has an ok variety, and I buy there because the people actually know the different between mip and fip and NPT.

I'll buy nails and drywall at HD. They can't screw that up. Much.

 

FF

[davelin315]

Draw out what you need and let me know. I can help you out with the plumbing. I've done a ton of it and messed up and learned a lot of lessons over the years.

[emissary]

Draw out what you need and let me know.  I can help you out with the plumbing.  I've done a ton of it and messed up and learned a lot of lessons over the years.

 

Well, my planned architecture is here:

http://reef.korff.org/pictures/Tank-In-Wal...t/180G_inwall_4

 

My rough idea of what I need is here:

There are three overflow bulkheads:

3 1.5" SCH80 bulkhead (Have 'em)

 

Inside the tank, I'll want elbows and strainers:

3 1.5" SCH80 90degree elbow mpt/slip

3 1.5" overflow strainer, slip (Marine Depot)

 

 

Two of these overflows combine into one and go to the skimmer:

2 1.5" SCH40 90degree elbow mpt/slip

1 1.5" SCH40 45degree elbow female slip/slip

1 1.5" SCH40 45degree wye female slip/slip

 

The third overflow goes to the refuigum and other places:

1 1.5" SCH40 90degree elbow mpt/slip

3 1.5" SCH40 ball valve

2 1.5" SCH40 Tee (do I need couplers?)

 

And the fresh saltwater intake from a 55G tank:

1 1" SCH40 bulkhead

1 1" SCH40 NPT male to female adapter

1 1" SCH40 90degree elbow

1 1" SCH40 ball valve

 

And finally the return coming off a mag 12:

1 3/4" SCH40 NPT female to slip female adapter

1 3/4" SCH40 true union check valve

1 3/4" SCH40 slip female to NTP female adapter

1 3/4" barb adapter

This takes me to flex tubing to the scwd, to more flex tubing...

1 3/4" barb adapter

And here I'm kind of lost as to what I need to do to get the water back in the tank.

 

There's also no mention here of unions except for the check valve, and maybe I'd want more? Also... the diagram shows "to drain" ... I'll have access to the underneath of a utility sink (standard drain setup) and would like to plumb into it somehow, but I'm not sure what to do here either.

 

Finally, of couse, I'll need:

bunch 1.5" SCH40 PVC pipe

bunch 1" SCH40 PVC pipe

[BeltwayBandit]

There's also no mention here of unions except for the check valve, and maybe I'd want more?  Also... the diagram shows "to drain" ... I'll have access to the underneath of a utility sink (standard drain setup) and would like to plumb into it somehow, but I'm not sure what to do here either.

 

Finally, of couse, I'll need:

bunch 1.5" SCH40 PVC pipe

bunch 1"  SCH40 PVC pipe

32896[/snapback]

 

for the drain line, the way you have it drawn it might cause you some problems. It appears to be a gravity drain. In order for that to work properly you need to have a drop of about 1-2" per 5' of pipe at a minimum to ensure that water will flow easily. To achieve this you might consider moving the drain line up higher on the return line. This is even more crucial since you want to go into an existing sewer drain. Ideally you would want to have an air gap in the system to absolutely prevent backflow, absent that a check valve should work. I am not familiar with pvc check valves to know how much pressure it takes to open them. For plumbing into the drain, simply remove the P trap on the bottom and insert a wye fitting. This will give you a place to tap into.

 

If you don't want to go the check valve route you could cap the open outlet on the wye, and end your discharge line with a hose connection that you can screw into the wye when needed, that way you can eliminate the need for backflow prevention.

 

Hopefully this makes some sense. I will look at the rest of your layout and offer any other comments I can think of.

 

BB

[BeltwayBandit]

Ok, I looked at your drawing and have a couple of comments. Don't tie the two drains to the skimmer section togeather. Just dump em both into the skimmer chamber.

 

Add at least 1 (actually 2 cause you can't do just 1) 90 in all of your drain lines. This will help quiet the drains, I made the mistake of straight piping mine the first time and it sounded like niagara falls. (You might be doing that already and just don't show it on the line diagram, if so ignore this comment)

 

You also might consider putting external Durso's on your overflows. This will also greatly help in reducing the noise generated by the falling water.

 

For getting the water back into the tank you can just build a hang on bracket out of pvc. For mine I used 3 90's and ended it with a hose fitting that acts like a nozzle. When you make it it should be just big enough to fit over the top frame of the aquarium. Then it just hangs in place and works great. The good thing is it is also very easy to change the position and direction of the flow. You just don't glue the bottom 90 on and you can rotate it 180 degrees to achieve the flow you want. The only downside is if you are pushing too much in the way of your return pump you might not be able to get away with this little trick and would have to glue the bottom 90 in place. You just have to play with it some and see what works. (If you don't like the stark white color you can "paint" it with purple primer and it will blend right in with the corraline algae.

___

| . | <--- Schedule 40 PVC

| . |_

| .

T <--- Hose connection

 

 

BB

[emissary]

for the drain line, the way you have it drawn it might cause you some problems.  It appears to be a gravity drain.  In order for that to work properly you need to have a drop of about 1-2" per 5' of pipe at a minimum to ensure that water will flow easily.  To achieve this you might consider moving the drain line up higher on the return line.  This is even more crucial since you want to go into an existing sewer drain.  Ideally you would want to have an air gap in the system to absolutely prevent backflow, absent that a check valve should work.  I am not familiar with pvc check valves to know how much pressure it takes to open them.  For plumbing into the drain, simply remove the P trap on the bottom and insert a wye fitting.  This will give you a place to tap into. 

I'm not sure I follow. My plumbing knowledge is VERY VERY green. I did just talk to my contractor though and he's going to hook up the drain end of things for me. He'll tap into the drain under the utility sink, run pvc around the room and install the necessary T connectors and U shaped thing (y'know, what you see under a sink). There'll be ball valves as described in the diagram still so from the overflow it looks like this:

 

into the elbow, down PVC. If the ball valve is open, it goes into the sump. If I close the ball valve everything is shut off.

 

I can then open the 2nd ball valve and water can flow into a bucket.

 

I can alternately open a 3rd ball valve and water will flow into the U shaped thing and then off to the drain. I *think* there is an air gap built in. In the wall next to the utilty stink is a PVC pipe a few feet tall with a black cap screwed into the end it looks like.

 

am I talking sense?

[emissary]

You also might consider putting external Durso's on your overflows.  This will also greatly help in reducing the noise generated by the falling water.

 

What is an external durso, and how would I set one up? Got URLs to diagrams/pictures? Are we talking about:

http://www.rl180reef.com/180/pages/standpi...ds/external.htm

Except instead of an overflow box, just having a T with a cap & air vent instead of a 90 degree elbow?

[BeltwayBandit]

What is an external durso, and how would I set one up?  Got URLs to diagrams/pictures?  Are we talking about:

http://www.rl180reef.com/180/pages/standpi...ds/external.htm

Except instead of an overflow box, just having a T with a cap & air vent instead of a 90 degree elbow?

32924[/snapback]

 

Thats it. Helps reduce the noise.

[BeltwayBandit]

I'm not sure I follow.  My plumbing knowledge is VERY VERY green.  I did just talk to my contractor though and he's going to hook up the drain end of things for me.  He'll tap into the drain under the utility sink, run pvc around the room and install the necessary T connectors and U shaped thing (y'know, what you see under a sink).  There'll be ball valves as described in the diagram still so from the overflow it looks like this:

 

into the elbow, down PVC.  If the ball valve is open, it goes into the sump.  If I close the ball valve everything is shut off.

 

I can then open the 2nd ball valve and water can flow into a bucket.

 

I can alternately open a 3rd ball valve and water will flow into the U shaped thing and then off to the drain.  I *think* there is an air gap built in.  In the wall next to the utilty stink is a PVC pipe a few feet tall with a black cap screwed into the end it looks like.

 

am I talking sense?

32919[/snapback]

 

Sounds good. The U shaped thing is called a P trap. It keeps water in it to provide a vapor barrier. This keeps sewage gasses from seeping back into the house through the open pipe. All of your plumbing fixtures have them.

[davelin315]

I would avoid any check valves. PVC check valves in my opinion are unreliable and severely reduce flow. The ones I am thinking of have a rubber flap with a piece of PVC in the middle and they are operated by gravity and flow. When you lose power, you won't create enough back pressure immediately to necessarily close the flap and also, you might not keep it closed after the rubber has had prolonged exposure to salt water. Also, it will severely restrict flow. I foresee a flow problem. You are using a mag 12 for your pump which I assume is rated at 1200gph at 0' head. It looks as if you will lose some gph going through the SCWD (I can't remember what gph they are supposed to be rated at) as well, so when it comes down to it, adding in the 4-5' head from the pump to the top of the tank, and then adding in another 3' for each part of the return that was suggested (which is probably the only way to do it if you're not drilled for a return) you're at what I would guess anywhere from 8-10' of actual head. This will reduce your gph down to around 500-600 gph. I used the head loss calculator at Reef Central to calculate it after I did my own calculations (Your Approximated Set Up). You may want to use two overflows, one going to your sump, one going to your refugium, and then use the other bulkhead for a return line. I would also drill the return line inside the tank just below the water line (it will allow a jet of water into your tank) so that when power goes out, you have a more reliable method for stopping back siphoning as it will break the siphon by allowing air in. Since you have 1.5" bulkheads in there, you might want to consider using reducer couplings to allow allow it to be the right size, or simply allow it to flow into the larger area and then plumb two returns from there. I don't know if a SCWD is submersible, but maybe you could simply plumb it inside your tank off of the bulkhead.

 

I agree that you should use an external durso standpipe on the outside as your type of overflow tends to be very noisy, but I don't know that you will have this problem with your current design. I would be concerned about the water level you will be reaching. If you lose all the pressure from your design that I think you will, with a 180g tank, which in your case will probably hold only about 150 gallons of water, you're only turning your tank over 3 times per hour, which is pretty tame all things considered. With that slow a turnover rate, your tank will barely fill above the top of the elbows you want to use on the inside. However, if you improve flow or use a larger pump, you will run into the problem that you are ending up with a very noisy system, hence building in the dursos will be a good idea from the get go.

 

One suggestion I would make, since flow is a potential problem I foresee, since you have an actual fish room, you might want to consider moving the sump and refugium out from under anything else and placing the sump on a slightly lower level than your tank so that you can reduce head loss from the pump. A side by side orientation would work just fine if you can fit it in, that would allow you to stick with the mag 12 for your system. Also, you might want to consider placing your refugium above your tank instead and using a smaller pump to pump water up to the refugium instead and allowing gravity to feed it back into the tank.

 

Just suggestions I have, the last one is kind of radical. I would definitely use spa-flex pvc in place of any other type of hose, too.

 

Sorry, I don't know how much sense I'm making, but if you want, ask me for clarification if you think you might buy into any of what I've said.

[emissary]

I would avoid any check valves.  PVC check valves in my opinion are unreliable and severely reduce flow.

I had read that. So I'm iffy on using them. I'm not sure I particularily need them either, my sump can handle any exra volume that shows up due to backflow. Still if you can believe advertising, these check valves are supposedly low flow loss:

http://www.marinedepot.com/md_viewItem.asp?idproduct=FT9144

 

 

you will be reaching.  If you lose all the pressure from your design that I think you will, with a 180g tank, which in your case will probably hold only about 150 gallons of water, you're only turning your tank over 3 times per hour, which is pretty tame all things considered.

Right and I'm not particuarily interested about tank turnover. I can upgrade to a Mag 18 if I run into problems due to lack of turnover. It's my understanding that turning the water over in the tank achieves very little in and of itself (correct me if I'm wrong). What I get is extra aeration (for dissolved oxygen content) and more water turbulence WITHIN the tank.

 

As far as aeration goes, I'm going to get a lot more from a skimmer than I will from increased flow, IMHO. And as far as water turbulence, I've got two Tunze Turbelle 6100s.

 

Also, you might want to consider placing your refugium above your tank instead and using a smaller pump to pump water up to the refugium instead and allowing gravity to feed it back into the tank.

At some point I may go for an over-the-tank refugium. It'll be a later project though.

 

Just suggestions I have, the last one is kind of radical.  I would definitely use spa-flex pvc in place of any other type of hose, too.

I'm using spa hose with my current setup... I may very well do the same for the new setup on the return.

[emissary]

Another random question. For the PVC overflow lines... should they terminate ABOVE or BELOW the water level in the sump?

[emissary]

Okay here's my new list based on comments. I've added McMaster Carr item numbers in case anyone has the copious amounts of free time and wants to double check my work.

 

There are three overflow bulkheads:

3 1.5" SCH80 bulkhead (from GlassCages)

 

Inside the tank, I'll want elbows and strainers:

3 1.5" SCH80 90degree elbow MPTxFPT 46885K126

3 1.5" overflow strainer, MPT (Marine Depot FT8577)

 

Two of these overflows go to the skimmer with external durso:

2 1.5" SCH40 female adapter 4880K85

2 1.5" SCH40 Tee 4880K45

2 1.5" SCH40 Cap 4880K55

6 1.5" SCH40 90degree female elbow 4880K25

 

(each pipe will go down the back of the tank, elbow under the tank, elbow down and elbow right before coming out into the sump. Too many elbows?)

 

The third overflow goes to the refuigum and other places:

1 1.5" SCH40 female adapter 4880K85

3 1.5" SCH40 Tee 4880K45

1 1.5" SCH40 Cap 4880K55

3 1.5" SCH40 ball valve (home depot?)

 

And finally the return coming off a mag 12:

1 3/4" barb adapter 5218K86

 

This takes me to flex tubing (where do I get the appropriate spa hose? I recall the stuff I got from HD before was maybe 1.5" or 2" ... not 3/4") to the scwd, to more flex tubing...

 

2 3/4" 90degree barb x MPT elbow 5218K86

2 3/4" 90degree female elbow 4596K13

2 3/4" Ball Socket x MPT connector (Marine Depot LL1319)

2 3/4" Ball Socket 90degree elbow (Marine Depot LL1325)

2 3/4" 6inch Ball Socket flexible tube (Marine Depot LL1311)

2 3/4" 3inch Ball Socket flare nozzle (Marine Depot LL1315)

 

And the fresh saltwater intake from a 55G tank:

1 1" SCH40 double slip bulkhead (Marine Depot FT1155)

1 1" SCH40 ball valve (home depot?)

2 1" SCH40 90degree elbow 4880K23

 

Finally, of couse, I'll need:

bunch 1.5" SCH40 PVC pipe (home depot)

bunch 1.0" SCH40 PVC pipe (home depot)

[davelin315]

Oops. The "radical" suggestion was to move the sump and the refugium. It was meant to be the last thing, and then I added the spa flex (not such a radical suggestion).

 

As far as the end point is concerned, above the water will create more splashing, below the water with the amount of air that will be introduced will elicit more microbubbles in the water. A compromise (that I'm not sure if you could do now) is a baffle that is set at an angle. This will allow the water to flow a bit more smoothly into your sump, eliminate some of the splashing, and also allow some of the bubbles that are created by the overflow to make it to the surface of the water by increasing the actual surface area.

 

Two of these overflows go to the skimmer with external durso:

2 1.5" SCH40 female adapter 4880K85

2 1.5" SCH40 Tee 4880K45

2 1.5" SCH40 Cap 4880K55

6 1.5" SCH40 90degree female elbow 4880K25

 

(each pipe will go down the back of the tank, elbow under the tank, elbow down and elbow right before coming out into the sump. Too many elbows?)

 

I'd say definitely. You are creating a lot of angles where you will not only decrease flow (which honestly should not be a big problem in your tank given the size of the overflows, multiplied by the number you have, and then considering the size of pumps you have/are considering for the future) but I would think you are also increasing the agitation in the piping (possibly a good thing). The more agitated the water is, the better the gas exchange that will occur, but in a pipe, I don't know how well that would work with the gasses being trapped. I would eliminate the 90 degree elbows and either replace them with spa flex or 45 degree elbows (won't change your cost as you still would only need 2 to make it under the tank).

 

This takes me to flex tubing (where do I get the appropriate spa hose? I recall the stuff I got from HD before was maybe 1.5" or 2" ... not 3/4") to the scwd, to more flex tubing...

 

2 3/4" 90degree barb x MPT elbow 5218K86

2 3/4" 90degree female elbow 4596K13

2 3/4" Ball Socket x MPT connector (Marine Depot LL1319)

2 3/4" Ball Socket 90degree elbow (Marine Depot LL1325)

2 3/4" 6inch Ball Socket flexible tube (Marine Depot LL1311)

2 3/4" 3inch Ball Socket flare nozzle (Marine Depot LL1315)

 

Whoa, that's a lot of elbows! You might want to check your flow again with the head loss calculator on reef central. As far as spa flex hose, I don't know if it's made in less than 1". I know that Lowes carries it at 1"+, but I haven't found it at a HD lately. With your order from McMaster Carr, you might want to check out the spa flex they have at the same time. Never hurts to have a little extra lying around for "oops" moments...

 

Good luck!

[BeltwayBandit]

Another random question.

[BeltwayBandit]

On another note. I was going down memory lane to my fluids class in college trying to remember how to do manual piping calculations, I'm an engineer I actually enjoy that sorta thing (I know I'm weird so don't tell me). And I came across some interesting stuff. First off your mag 12 is overkill. A SCWD at 720 GPH switches in 4 seconds. The website for them says you can push up to 1400 GPH through but it switches very fast, just something to consider.

 

Another option would be to plumb the scwd in on a closed loop and use the mag 12 for your circulation through the sump and refugium.

[davelin315]

I did a quick head loss calculation and with the plumbing you're using, you're still at only 589 gph with about 10' of head (don't know how much the scwd will cost you as well). That's still not a whole lot of flow, so I don't think you need to worry about overkill.

[emissary]

I did a quick head loss calculation and with the plumbing you're using, you're still at only 589 gph with about 10' of head (don't know how much the scwd will cost you as well).  That's still not a whole lot of flow, so I don't think you need to worry about overkill.

 

10' ?! It's about 3 feet to the scwd and an additional 2.5 feet (diagonalish) to the top of the tank.

[davelin315]

Each 90 degree elbow adds 1', and there is loss of head for each vertical and horizontal foot it travels. Add in the ball valves and the unions which sometimes reduce the size within them a bit, and you have much less flow. When gph is listed, it's listed from the pump itself, every inch you get away from the pump, you lose some. Also, with regular flexible tubing, even braided which will avoid kinks, you are losing a lot of flow if it's in the feed line (not in your case) as the suction will contract the hose. Also, the barbs themselves will reduce flow as they reduce 3/4" ID hose down another 1/16" or more. 589 is probably generous seeing as the SCWD is typically barbed and the switching mechanism inside will most likely reduce your flow.

 

You should really check out the head loss calculator. It's on the left side menus of the reef central site. It's based on a logarithm that was created on RDO which is a good site as well.

[emissary]

Each 90 degree elbow adds 1', and there is loss of head for each vertical and horizontal foot it travels.  Add in the ball valves and the unions which sometimes reduce the size within them a bit, and you have much less flow.  When gph is listed, it's listed from the pump itself, every inch you get away from the pump, you lose some.  Also, with regular flexible tubing, even braided which will avoid kinks, you are losing a lot of flow if it's in the feed line (not in your case) as the suction will contract the hose.  Also, the barbs themselves will reduce flow as they reduce 3/4" ID hose down another 1/16" or more.  589 is probably generous seeing as the SCWD is typically barbed and the switching mechanism inside will most likely reduce your flow.

 

You should really check out the head loss calculator.  It's on the left side menus of the reef central site.  It's based on a logarithm that was created on RDO which is a good site as well.

 

Yeah I've used the head loss calculator before. I was talking to steve outlaw this weekend who's using a SCWD. He confirms that it in fact kills flow. I'm still not sure why I *need* lots of flow though.

[davelin315]

I know that you said you've got a few pumps that will agitate your system, but there are many reasons for having a high turnover rate, at least in my own opinion.

 

The first reason is that when water is removed to a sump, it becomes highly agitated. The highest gas exchange rate is obviously at the surface of the water, but as it passes through different parts of your system, it will have more gas exchange. Turbulence in a sump is different from surface agitation in a display. The turbulence will in effect knock some gasses right out of solution. The increased turbulence causes more bubbles in the water and more mixing, which causes increased surface area. In essence, you are mimicing the effects of a wet dry filter by providing more surface area for the gas exchange. That is why on my old system I used a trickle filter without bio-balls. The drip plate allowed the water to have an incredibly high exchange rate with gasses. If you decrease the flow to your sump, you are decreasing the gas exchange. That is not to say that your tank won't be good with low flow, it just kind of negates one of the reasons for having a sump, and more closely resembles a closed system.

 

The next reason has to do with mechanical filtration. I don't typically use any sort of mechanical filtration on my systems, but many people do, and the place to do this is generally in the sump unless you are going to resort to a hang on tank filter. Even without using mechanical filtration, a sump serves as a collection place for detritus. Between baffles you are looking to create an area of low flow so that detritus will settle out and microbubbles will float to the surface. If your main tank is not agitated enough and the flow is not enough, very little of the detritus will be taken into the sump, and will instead remain in the display tank.

 

The last reason in my opinion for a higher turnover rate is that the fewer pumps in the system, the better. If you have a pump that is going to turn your tank over 10x per hour, then you can use any additional pumps merely as wave makers (which will also prevent detritus from settling on your corals and rock, which in turn will be a preventative measure for combatting nuisance algaes). If you have low flow going through your tank then you have to rely more on the additional pumps to provide that flow.

 

For me, the higher the turnover rate the more efficient a system you have. I think it better utilizes the additional capacity you have since more water is going through it. For instance, you have a refugium on your system. As you have three bulkheads for drainage, most likely only 1/3 of your water will pass into the refugium each trip. With a flow of 589 gph, you are getting less than 200 gallons of water passing through your refugium each hour. While this may be desireable for algae growth, think of how little water is actually passing through the refugium. This means that a very small percentage of your water is passing through your refugium each hour. The more water flow through your refugium, the better able the inhabitants will be to do their jobs, whether it be pods reproducing or algaes filtering the water, all of them need good flow to survive.

 

Again, most of this is just my own personal thoughts, I am sure that others have equally if not more convincing rationales for low flow, but for me, despite the fact that a tank with a sump is not a "closed" system per se, it essentially still is, so it's best to utilize all of the water capacity to its fullest, which again, to me, means letting it flow.