90G drain flow rate

nube · 04/23/2010, 07:17 AM

I'm new to the hobby and am setting up a 90G DT with a 55G sump in the basement below. The DT was "Reef Ready" for two bulkheads in the bottom of the overflow chamber. One 1" and one 3/4". I'm using both for drains to the sump. The 3/4" is running to a bulkhead in the sidewall of the sump feeding the "fuge" section. The 1" is running to the skimmer section and entering from above (no bulkhead). Both lines are valved. I'm using the "Durso Design" stand pipes in the overflow chamber. The 1" bulkhead has a 1 1/4" thin wall pipe and the 3/4" bulkhead has a 1" thin wall pipe. I've finished the plumbing and have filled the system with fresh water for "testing'. The good thing is I have no leaks. The troubling thing is I'm dragging a lot of air from the overflow chamber to the sump through both drain lines. I have experimented with different stand pipe air vents and heights, etc with no success. I have run the system and calculated that I'm getting 625 GPH of water back to the display tank with both drain valves open. That flow seems to be on the low side of what is reccomended (from what I read???) Here is what I think I see happening and need your advice on. When the system pump is pumping full bore back to the DT and I'm getting the 625 GPH the overflow chamber baffle can't handle that flow rate through the oval shaped holes. (There are two rows of holes, one near the top and one near the bottom). There is some water breaching the top of the overflow baffle as well. Even though there is some addidtional water flowing over the baffle top the standpipes are still starving for water and therefore "dragging" air to the sump. If my contention is correct then it seems I would have but two options.The first would be to add more holes in the factory overflow baffle or to valve back everything, drains and return. If I valve back I don't believe I'll get the recommened flow through the system. What am I missing? I can post photos if needed. Help Please! Curt

kclewis · 04/23/2010, 07:46 AM

i think the easy fix is to buy a larger return pump.

nube · 04/23/2010, 09:09 AM

I think you've misread my post or I haven't explained it well enough. The problem I seem to have is the overflow chamber isn't passing enough water through it to satisfy the volume the pump needs.

jupiter · 04/23/2010, 09:39 AM

You'll probably have to post pics. If I understand you correctly, the bottleneck in your design is that holes to feed the OF are few or not large enough. So, your standpipes could potentially handle the entire flow, they just don't get enough water.

Did the manufacturer or LFS tell you how much the OF box was rated for?
Your flow rate through your system should at least match your skimmer output. The two standpipes together can handle about 850 gph using gravity feed. If it's your OF box, you'll need to modify it.

However, it also sounds like you have a siphon going on if water can actually breach the OF box but still causes air sucking. On your Durso, is air allowed into the standpipe via a hole, tubing, etc.? What sounds like to me is that the standpipe is filling with water, the air cuts out, and the standpipe sucks the water down like a toilet. This leaves the OF with no water and it sucks air.
Ideally, water should flow into the OF box, and rise to about the level of the horizontal part of the elbow and stay there. Is your water rising above he entire standpipe? It is also possible that the pump is too powerful for the standpipes and floods the Durso faster than it can handle the water flow.

These are just suggestions to think about.

nube · 04/23/2010, 11:44 AM

Quote:

Originally Posted by jupiter

You'll probably have to post pics. If I understand you correctly, the bottleneck in your design is that holes to feed the OF are few or not large enough. So, your standpipes could potentially handle the entire flow, they just don't get enough water.

That is what i think is happening

Did the manufacturer or LFS tell you how much the OF box was rated for?

No and I didn't know to ask at the time

Your flow rate through your system should at least match your skimmer output. The two standpipes together can handle about 850 gph using gravity feed. If it's your OF box, you'll need to modify it.

However, it also sounds like you have a siphon going on if water can actually breach the OF box but still causes air sucking. On your Durso, is air allowed into the standpipe via a hole, tubing, etc.? What sounds like to me is that the standpipe is filling with water, the air cuts out, and the standpipe sucks the water down like a toilet. This leaves the OF with no water and it sucks air.
NO siphon going on. I've tried different size holes and different number of holes in the Durso air cap

Ideally, water should flow into the OF box, and rise to about the level of the horizontal part of the elbow and stay there. Is your water rising above he entire standpipe? It is also possible that the pump is too powerful for the standpipes and floods the Durso faster than it can handle the water flow.

If the two standpipes can gravity feed 850GPH and my pump is pumping 625 GPH back to the DT then it seems to me that the pump is not the problem. I believe you're correct in your assesment that the OF cannot handle enough water. The water in the OF does not rise above the durso elbow. But, if this tank was sold as reef ready and the recommened flow rates are what we read then why are there not enough holes in the overflow baffle to handle the necessary flow??? Do you have or do you know of a recommended size or placement of additional holes to the OF?

These are just suggestions to think about.

nube · 04/23/2010, 06:20 PM

BUMP still looking for answers!

dpenning · 04/23/2010, 07:49 PM

I'm a nube too so offer this input that should be taken with a grain of salt. When the LFS set up my 110 gal with a durso type drain pipe it would go along for a few minutes then make this awful noise that sounded like an airplane toilet flushing. He went from a mag 9 down to a mag 7 return pump and it helped but I didn't think I was getting enough flow. I went back to the mag 9 and through playing around with it found that restricting the flow from the drain pipe kept everything in balance. My technical solution? I stuffed a piece of an old snorkle in the drain pipe to help restrict flow. Nice and quiet.

gonpostal · 04/23/2010, 09:40 PM

IMO, you should slow down the flow going through your sump. You don't need that much flow, and your skimmer will probably be more efficient if the flow is slower. I would put a gate valve on the output of your return pump to slow down the flow. You can use powerheads to move the water in your tank. The "turnover rate" that you read about includes your powerheads, not just what goes down your overflow and through the sump.

kclewis · 04/24/2010, 08:59 AM

I still thinK you need a larger pump. Sounds to me your durso is not getting enough flow to maintain water level. your overflow should be able to handle way more than 650 as it is without adding more holes.

04/23/2010, 07:17 AM	#1
nube Registered Member Join Date: Feb 2010 Posts: 22	90G drain flow rate I'm new to the hobby and am setting up a 90G DT with a 55G sump in the basement below. The DT was "Reef Ready" for two bulkheads in the bottom of the overflow chamber. One 1" and one 3/4". I'm using both for drains to the sump. The 3/4" is running to a bulkhead in the sidewall of the sump feeding the "fuge" section. The 1" is running to the skimmer section and entering from above (no bulkhead). Both lines are valved. I'm using the "Durso Design" stand pipes in the overflow chamber. The 1" bulkhead has a 1 1/4" thin wall pipe and the 3/4" bulkhead has a 1" thin wall pipe. I've finished the plumbing and have filled the system with fresh water for "testing'. The good thing is I have no leaks. The troubling thing is I'm dragging a lot of air from the overflow chamber to the sump through both drain lines. I have experimented with different stand pipe air vents and heights, etc with no success. I have run the system and calculated that I'm getting 625 GPH of water back to the display tank with both drain valves open. That flow seems to be on the low side of what is reccomended (from what I read???) Here is what I think I see happening and need your advice on. When the system pump is pumping full bore back to the DT and I'm getting the 625 GPH the overflow chamber baffle can't handle that flow rate through the oval shaped holes. (There are two rows of holes, one near the top and one near the bottom). There is some water breaching the top of the overflow baffle as well. Even though there is some addidtional water flowing over the baffle top the standpipes are still starving for water and therefore "dragging" air to the sump. If my contention is correct then it seems I would have but two options.The first would be to add more holes in the factory overflow baffle or to valve back everything, drains and return. If I valve back I don't believe I'll get the recommened flow through the system. What am I missing? I can post photos if needed. Help Please! Curt

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04/23/2010, 07:46 AM	#2
kclewis REEFER Join Date: Apr 2002 Location: Beautiful Bargersville, IN Posts: 383	i think the easy fix is to buy a larger return pump.

04/23/2010, 09:09 AM	#3
nube Registered Member Join Date: Feb 2010 Posts: 22	I think you've misread my post or I haven't explained it well enough. The problem I seem to have is the overflow chamber isn't passing enough water through it to satisfy the volume the pump needs.

04/23/2010, 09:39 AM	#4
jupiter Moved On Join Date: Jun 2002 Location: Toronto, ON, Canada Posts: 181	You'll probably have to post pics. If I understand you correctly, the bottleneck in your design is that holes to feed the OF are few or not large enough. So, your standpipes could potentially handle the entire flow, they just don't get enough water. Did the manufacturer or LFS tell you how much the OF box was rated for? Your flow rate through your system should at least match your skimmer output. The two standpipes together can handle about 850 gph using gravity feed. If it's your OF box, you'll need to modify it. However, it also sounds like you have a siphon going on if water can actually breach the OF box but still causes air sucking. On your Durso, is air allowed into the standpipe via a hole, tubing, etc.? What sounds like to me is that the standpipe is filling with water, the air cuts out, and the standpipe sucks the water down like a toilet. This leaves the OF with no water and it sucks air. Ideally, water should flow into the OF box, and rise to about the level of the horizontal part of the elbow and stay there. Is your water rising above he entire standpipe? It is also possible that the pump is too powerful for the standpipes and floods the Durso faster than it can handle the water flow. These are just suggestions to think about.

04/23/2010, 06:20 PM	#6
nube Registered Member Join Date: Feb 2010 Posts: 22	BUMP still looking for answers!

04/23/2010, 07:49 PM	#7
dpenning Registered Member Join Date: Apr 2010 Posts: 2	I'm a nube too so offer this input that should be taken with a grain of salt. When the LFS set up my 110 gal with a durso type drain pipe it would go along for a few minutes then make this awful noise that sounded like an airplane toilet flushing. He went from a mag 9 down to a mag 7 return pump and it helped but I didn't think I was getting enough flow. I went back to the mag 9 and through playing around with it found that restricting the flow from the drain pipe kept everything in balance. My technical solution? I stuffed a piece of an old snorkle in the drain pipe to help restrict flow. Nice and quiet.

04/23/2010, 09:40 PM	#8
gonpostal Registered Member Join Date: Mar 2009 Location: Wilmington, NC Posts: 550	IMO, you should slow down the flow going through your sump. You don't need that much flow, and your skimmer will probably be more efficient if the flow is slower. I would put a gate valve on the output of your return pump to slow down the flow. You can use powerheads to move the water in your tank. The "turnover rate" that you read about includes your powerheads, not just what goes down your overflow and through the sump.

04/24/2010, 08:59 AM	#9
kclewis REEFER Join Date: Apr 2002 Location: Beautiful Bargersville, IN Posts: 383	I still thinK you need a larger pump. Sounds to me your durso is not getting enough flow to maintain water level. your overflow should be able to handle way more than 650 as it is without adding more holes.