GPH and Gallon Ratings for Equipment

[The Kerrnel]

I've often wondered, but never really needed to know, so never bothered to check up on this stuff, but when you get equipment that gives a gallon rating, is that often a low-ball estimate?

 

For example, I'm browsing for an overflow box for my 55g tank as I piece things together to get it operational. I've seen a series of them from CPR Aquatic and found one for $59+shipping that is "rated" for a 50g tank and provides a 300gph flow rate. I figure general rule of thumb is 6-10x turnover bare minimum for a tank is the ballpark to be in, but seeing as this is water that will be hitting the sump as opposed to swirling around in the tank will that suffice? I generally run about 30-50x flow in my 10g, which includes a Rio nano and a Whisper 20 for filtration.

 

On the flip-side, the next model up is rated for 90g with 600gph. Is that too much, keeping in mind this is water going into the sump, not just moving around the tank? I suspect the skimmer power will have something to say about that?

 

And I guess the last question, does the return pump gph need to match the overflow? Part of me thinks this is a stupid question and that the answer is yes, but the other part of me says it's better to ask than stay ignorant.

 

Thanks

[jakaufman]

I am not sure about the general flow ratings on powerheads and overflows, but for your return pump, it should be the same or less than your overflow (taking head loss into account). It is fairly easy to just think what would happen if you pump more water into your tank than you can drain out of it

[treesprite]

Don't get a CPR overflow or other brand of that type overflow. They work supposedly better than U-tubes and I like mine, but at the same time, the potential for floods is higher because the siphon relies on the aqualifter pump (or powerhead) that has to be used and those do tend to fail like any other piece of equipment. Best idea is to have the tank drilled.

[The Kerrnel]

Don't get a CPR overflow or other brand of that type overflow. They work supposedly better than U-tubes and I like mine, but at the same time, the potential for floods is higher because the siphon relies on the aqualifter pump (or powerhead) that has to be used and those do tend to fail like any other piece of equipment. Best idea is to have the tank drilled.

 

I thought the siphon relied on gravity/the usual, and that the pump was only to ensure the siphon was primed after a power outage? I know they recommend it, but I didn't think it was mandatory.

 

I was always under the impression (and still am) that an overflow box is the safest way to go to avoid floods? Obviously diligent planning and all that should avoid the same as well, but without any mechanical accessories, an overflow should just stop siphoning when the water level gets too low (which is usually a lot higher than if you had drilled the tank).

 

I had decided a while ago that I wasn't going to drill this tank, so that leaves me looking for overflow boxes...

[onux20]

I thought the siphon relied on gravity/the usual, and that the pump was only to ensure the siphon was primed after a power outage? I know they recommend it, but I didn't think it was mandatory.

 

I was always under the impression (and still am) that an overflow box is the safest way to go to avoid floods? Obviously diligent planning and all that should avoid the same as well, but without any mechanical accessories, an overflow should just stop siphoning when the water level gets too low (which is usually a lot higher than if you had drilled the tank).

 

I had decided a while ago that I wasn't going to drill this tank, so that leaves me looking for overflow boxes...

Kernel,

I can speak from experience. I had the CPR overflow, small air bubbles get caught in the u-tube and can build in to one big bubble that may break the siphon. It happened while I was an hour away from my tank. My neighbor was tank sitting and called in that the water level was really low. Long short, the siphon was broken but the retun pump kept pumping. Luckily, I did not cause a fire when my power strip shorted out. Thank goodness my neighbor was being diligent and checked the tank as requested.

That is just my experience. I will agree with Treesprite, get it drilled if possible.

Ron

[YBeNormal]

Overflows rely on a siphon to keep the water flowing. Air bubbles can accumulate in the siphon area and reduce or stop the flow entirely. Drilled tanks rely on only on gravity and are less likely to fail. Given the choice, I'd go with drilled tanks anytime.

[shawns]

300gph through a sump for a 55g tank should be fine. i do about 600gph through a 90g tank. there will need to be additional ph's to increase water movement.

 

i've used lifereef boxes and been happy.

 

drilled tanks are better then the overflow box.

 

what is that monkey doing to that football in your avatar picture??

[gastone]

300gph through a sump for a 55g tank should be fine. i do about 600gph through a 90g tank. there will need to be additional ph's to increase water movement.

 

i've used lifereef boxes and been happy.

 

drilled tanks are better then the overflow box.

 

what is that monkey doing to that football in your avatar picture??

 

 

I agree with Shawn.

 

G.

[ErikS]

Well in reality anything more through the sump than what the skimmer requires is a waste.....but I would also agree, a drilled tank is optimum, though not necessary. A lifereef/hurricane/amiracle style overflow is completely reliable. Five years without a single mishap tells me an hang on overflow can be pretty reliable.

[The Kerrnel]

Sometimes I hate this hobby. I now understand the problems with losing a siphon in an OTT box...pump water back into the tank with no siphon and poof, instant flood.

 

I've always thought drilling the tank causes structural issues, but I guess if thousands of hobbyists do it without problems, it can't be that bad. If one were to drill the tank, would it be better to have an overflow box inside the tank so that it can skim, or are there effective things I can use to accomplish the same thing? I've seen the pvc with holes in the top but never really figured out if it worked as advertised or not.

[Integral9]

If you have your tank drilled on the back wall, you have two options. I don't recommend drilling through the bottom as it's usually tempered glass and will shatter (then you get to buy a new tank.. how awesome is that!?)

 

1. You can install an overflow box to skim which will take up a bunch of room and / or provide a shaded area depending on if you get the kind that goes all the way down to the bottom or not.

 

2. You can use an elbow on each hole to reach up to the surface to skim.

 

Most people choose the later. I would. Mainly because it's cheaper, fish don't get lost in box you can barely fit your hand into, and it doesn't take up room or cast hardly any shadow.

 

The PVC with holes drilled in the top does two things. Inside the tank, the PVC reaches up to the surface in the tank to skim off the surface. Outside the tank, the PVC reached above the water line w/ a cap and hole drilled into it to break a siphon and eliminate the slurping / sucking noises.

 

btw.

It looks like your monkey's got his "O" face on....

Edited April 23, 2008 by Integral9

[The Kerrnel]

If you have your tank drilled on the back wall, you have two options. I don't recommend drilling through the bottom as it's usually tempered glass and will shatter (then you get to buy a new tank.. how awesome is that!?)

 

I'd be scared to drill through the bottom...just asking for a flood that way. New tank, new floor...lol

 

I like the pvc elbow idea...I guess wrap some coarse mesh around the top of the opening to prevent fish loss...

 

btw.

It looks like your monkey's got his "O" face on....

 

The monkey is merely hiking the ball.

[Integral9]

I like the pvc elbow idea...I guess wrap some coarse mesh around the top of the opening to prevent fish loss...

Now you're cooking w/ propane.

[shawns]

The monkey is merely hiking the ball.

 

sure. right.