too much flow

[fishdrummer]

im adding a dart to my 180 gallon in hopes of adding sps .

 

currently i am running 2534 gph (mk4 and 40 rxlt)

 

with the dart at 3600 .. my total would be 6134 gph ... would this be too much ??

thanks

Edited May 4, 2007 by fishdrummer

[jamesbuf]

what size overflows do you have to support that much turnover?

[Jager]

as james asked above, are you running the dart as a closed loop?

 

depending on how your running it yes it can be way too much flow (specially if your using a standard AGA/Perfecto tank and running the dart as a return pump.) that being said. if you use a closed loop with 6-10 outlets in it or more you can use the dart without worry. you just need to plan it out well, and use some flexible parts at the outlets to allow for changes.

 

my 55 gallon had a bit over 4000gph in tank current which was 47x in a closed loop setup,

 

done correctly there will be an incredible chaotic flow as the various outlet streams hit each other and mix. and the dart is very well suited to a CL being so quiet.

 

give us an idea how you want to do the plumbing or how you plan to run the various pumps and we can help quite a bit more.

[fishdrummer]

thanks. i will have three overflows for the iwaki and mk4 .. two one inch bulkheads spaced about a foot apart just under surface and one corner overflow draining to the sump (ill have a big 150 stock tank) .

 

the dart is hooked up to a 4 way oceanmotions.. i intend for it to be closed loop.

 

my thinking is to plumb in (4) one inch bulkheads to accomodate the oceanmotions setup.

 

the drain for it will be 4 inch.

[Jager]

thanks. i will have three overflows for the iwaki and mk4 .. two one inch bulkheads spaced about a foot apart just under surface and one corner overflow draining to the sump (ill have a big 150 stock tank) .

 

the dart is hooked up to a 4 way oceanmotions.. i intend for it to be closed loop.

 

my thinking is to plumb in (4) one inch bulkheads to accomodate the oceanmotions setup.

 

the drain for it will be 4 inch.

 

 

a dart is standard 2" plumbing if my memory serves, so you are probably better off doing 2 2" drains to the dart .

 

as for the returns why not go over the tank and return in a manifold that way? is that how your other pumps are setup so its not feasible? if you can avoid drilling your tank and still maintaining the look you want its the "safest" but id plum any below waterline plumbing with ball valves and unions to facilitate removal in case of any issue.

 

drilling the backglass a bit higher and then hiding the plumbing using black tubing and some zip ties to hold on LR is also an option. that way if you run into a leak, you dont have to totally drain the tank.

 

 

HTH

[fishdrummer]

 

i added a few pictures showing my current configuration.

 

i think adding the bulkheads would be cleaner ..

[fab]

Unless I am missing something, your current flow is 14 turnovers per hour. That is a lot. It is halfway between the two ends of the range I've seen published in reference to desired flow rates for corals: 10x - 20x.

 

Going up to 6000+ gph puts you at 34 turnovers which is 50% higher than the highest number (20x) I've ever seen recommended.

 

Regardless how you divide the flow down, 4 way or 8 way, you will be producing some pretty disturbing currents, pardon the pun. I think you will be battering your livestock with very high speed water flow, including the sps corals, even if you can keep it from developing laminar flow anywhere in the tank. Plus you will add a sizeable slug to your electric bill, probably for no real benefit. I'd consider first, don't add anything. Your current 14x is probably about right. If you decide you must add more flow, then consider capping it at about 20 turnovers per hour (3600 gph) and seeing if even that is too much flow for a 180 gallon tank. You are almost there with your current setup at 2500 gallons per hour.

 

good luck,

fab

Edited May 5, 2007 by fab

[Rascal]

I agree with Jager on the 2 x 2" drains. If it were just a simple closed loop, I would also strongly suggest the return manifold sitting on top of the tank, but I can see why you might not want to do that with the OM 4-way.

 

As far as flow, I'm afraid I have to disagree with Fab on this one. I don't think 35X turnover is even approaching too much flow for an sps tank. There are lots of folks out there now who are running at least this much and more. It's all about how it is delivered. More flow, less velocity, as they say.

[Jager]

fab see above, i ran 47x turn over in my 55 gallon.

 

the reason for the 2 2" drains is to relieve suction if any fish get stuck to one of the 2 inch pipe strainers.

 

bulkheads ould be fine, just be careful in placement so you do not overly stress the tank.

 

tank turnover numbers are difficult to put a cap on. the corals and fish are used to 1000s of turnover per wave series. i am slated to move to 11000 gph through my 75 gallon tank which puts me at 146x tank turn over.

 

this will be using the mj1200 mods i have plus a set of darts or a barracuda.

 

being that im moving to a 150xh i may up the turnover number again so that i at least stay over 100x turnover.

 

each outlet in my CL should be around 700-800gph since ill have 12-15 of them in a manifold.

 

 

happy surfing :P

[fab]

I stand corrected, Rascal.

 

I did some looking around and found some references to folks with 40+ turnovers and even higher. I have no way of vetting these anecdotal instances of nternet reference, though. The people using these very high turnover rates do claim success. The 10x-20x range I referred to came from published [book] literature.

 

I will take issue with your last remark: "More flow, less velocity, as they say." That is absolutely incorrect! What you may have meant to have said is more cross-sectional area [that constrains the flow], the less velocity. That would have been correct.

 

If you work with a given cross-sectional area and pass a flow of water through it, the velocity of the water through that area will increase linearly with increases in the volumetric flow rate. If you increase the cross-sectional area and hold the volumetric flow rate constant, the velocity will reduce linearly with the reduction in volumetric flow rate.

 

fab

Edited May 6, 2007 by fab

[Jager]

I stand corrected, Rascal.

 

I did some looking around and found some references to folks with 40+ turnovers and even higher. I have no way of vetting these anecdotal instances of nternet reference, though. The people using these very high turnover rates do claim success. The 10x-20x range I referred to came from published [book] literature.

 

I will take issue with your last remark: "More flow, less velocity, as they say." That is absolutely incorrect! What you may have meant to have said is more cross-sectional area [that constrains the flow], the less velocity. That would have been correct.

 

If you work with a given cross-sectional area and pass a flow of water through it, the velocity of the water through that area will increase linearly with increases in the volumetric flow rate. If you increase the cross-sectional area and hold the volumetric flow rate constant, the velocity will reduce linearly with the reduction in volumetric flow rate.

 

fab

 

 

er being that i havea high turnover i believe that rascal meant that in the sense that i take that as, unfortunatly i think he left off part of the line.

 

I know that line as the more chaotic flow the less perceived velocity of the water. that works out because although the water is churning in all different directions, the net effect on the object in the water is negligible in a given area due to the constant changing flow.

 

anyway, back on point of the thread. you can have all the flow you want in a fish tank as long as its not laminar flow. 146 times tank turn over or 11000 gph in a 75 gallon seems ludicrous, however with well thought out and chaotic flow patterns ( injecting air into the pumps helps discern flow paths very well to aid in placements) you can have even the most ungainly fish and the more difficult to keep corals happy.( i back that up by saying i keep puffers and have for years with CL setups with extremely high flow without issue. some gonipora colonies as well which hate high flow thats laminar.)

 

 

the best setup is a CL with an OM or other flow altering device that cycles, that way you can control wave patterns . electronic ball valves are on my list to play with to so just that by shutting off some areas behind the rocks at night and to change the force of flow similar to the OM surge thing Dan linked above. you may want to look into that as well, they can be pricey though.

HTH

[Rascal]

I stand corrected, Rascal.

 

I did some looking around and found some references to folks with 40+ turnovers and even higher. I have no way of vetting these anecdotal instances of nternet reference, though. The people using these very high turnover rates do claim success. The 10x-20x range I referred to came from published [book] literature.

 

I will take issue with your last remark: "More flow, less velocity, as they say." That is absolutely incorrect! What you may have meant to have said is more cross-sectional area [that constrains the flow], the less velocity. That would have been correct.

 

If you work with a given cross-sectional area and pass a flow of water through it, the velocity of the water through that area will increase linearly with increases in the volumetric flow rate. If you increase the cross-sectional area and hold the volumetric flow rate constant, the velocity will reduce linearly with the reduction in volumetric flow rate.

 

fab

 

 

Fab:

 

You are correct of course. The phrase is aspirational, not descriptive. In other words, the goal is to increase the flow without increasing the velocity, which can be achieved by increasing the cross sectional area.

 

I think almost all of the books I have read recommend the same, 10-20 gph was the standard for many years. Check the copyrights on those books, though. Advances in the hobby have changed that thinking, I believe, and many of those authors (Calfo, Fenner, Tullock, etc. . . ) now recommend higher flow if it can be achieved without too much velocity. I know in Paleta's book "Ultimate Reef Aquariums", he definitely advocates higher flow. I have about 35X turnover in my tank, which is mostly sps but some softies (GSP, shrooms, xenia) and a some lps. By direction of the flows and placement of corals, I try to place each animal in the spot where it will do best. I even have 4-5" DSB in the display and have been able to manage that much flow without a sandstorm.

[dandy7200]

I can't imagine running a tank with corals at anything less than 30x turnover. 10x through the overflows minimum and 20x intank circulation IMO/IME. I have around 40x turnover in my softie tank and 50x in my SPS and 120x in my frag tank. The idea has become popular (books and internet bb's) that you only need 3-5x turnover through the overflows. This is a awful idea IMO/IME. Sure it helps with micro bubbles in the display but so does properly configured sump and tuned skimmer. Get that crap out of the display and into the sump so it can be processed correctly by mechanical filtration as quick as possible regardless if you have a DSB or BB tank. I don't have a problem with "More flow, less velocity, as they say." Same concept as a stream pump vs a powerhead. Drop a couple Tunze 6080's in that 180 and get the same flow as a dart for a lot less money and 30w power, just a thought.

 

I guess really to answer your question though: Yes you can have too much flow and strip the tissue off the corals but you are far from approaching that number as long as the flow is well dispersed throughout the tank.

[fab]

Dandy7200,

 

I am interested in your concern to have at least 10x in the overflow-sump-return portion of the overall flow system. Would you please elaborate on your rationale for that? I am facing a decision point in my setup that is concerned with this very issue.

 

Here are my presumptive thoughts on this. My own thoughts raise questions. Perhaps you have the answers.

 

It seems to me that the water that goes through the sump both provides for water motion and is made available for processing; e.g., mechanical filtration, biological filtration, protein skimming, chemical reactors, UV sterilization, heating and cooling, and for injection from refugia, freshwater water top-off and oxygenation. There are probably more things that could be done via the sump. On the other hand, the water flowing through a closed loop only provides water motion.

 

The water that goes into the sump is processed at various different rates by the various devices that draw water from the sump, process it and return the processed effluent to the sump for eventual return to the display tank. Not all the water in the sump will necessarily be processed during each pass through the sump. This is because some of the processes are just sampling the water in the sump, not being in-line where they process all of it. Thus any water that makes its way into the sump that doesn't get processed on a given pass is essentially acting as though it is just in a closed loop, except that it is getting a shot at oxygenation in the sump that it would not get in a closed loop.

 

Therefore, it seems to me that once you exceed the flow rate capacity of the sump-based processing then you are just getting the same effect on the excess flow above that capacity that you would get with a closed loop? If that is the case then why provide much more overflow-sump-return capacity than you have in processing capacity? Now, on the other hand, if the added oxygenation is sufficient reason to increase overflow-sump-return flow rate then why not use a very large sump and pass all the flow through a sump including that flow you would otherwise provide with a closed loop? That way the entire flow would benefit from the added oxygenation value of the sump path over a closed loop path.

 

My personal experience tells me that a simple common sense analysis is usually either right or it is wrong because other important factors are at play that the "simple" analysis left out.

 

So why is it important to exceed the sump processing rates by any significant margin? And, if it is valuable to do so then what is the rationale for providing separate closed loop flow over providing the full flow rate through an open overflow-sump-return loop?

 

fab

[dandy7200]

If the "crap" gets in the sump it has the "ability" to be processed. It doesn't mean it will but if it doesn't get there in the first place.....

 

You hit the nail on the head as far as the benefits of oxygenating the water .