Help with water pump please

Gabe · 01-09-2003, 09:41 PM

Im adding a sump to my 50 gallon tank. Im using a cpr over flow that takes out 300 gallons per hour. My question is what kind of pump I should use(have decided upon internal for sure) to return the water back to the main tank, but more importantly how strong? I know I have to pump the water up over 4feet so i need a relatively strong one, but how do I balance the pump with the overflow. The dilema is this: if the pump is to strong it will drain the sump dry, if the pump isnt powerful enough, the cpr siphon will siphon itself dry because the water lever in the main tank will drop. Can somebody pleasssssse clarify matters with me. Any help would be appreciated, thanks.

Skunk Clown · 01-09-2003, 10:30 PM

ummm, i didnt really follow your thoughts. but let me stop you, i had........ yes had a cpr overflow, and i would rather have heaters and power heads hanging in my tank rather than one of these piles!

**scubadude** · 01-10-2003, 12:49 AM

Sounds like you have a couple of dilemas, First off a good pump for you would be something like a Mag7 at the minimum it produces 480GPH @ 4' head and you can put a ball valve on your output side and throttle it down to meet your Overflow demands. You could do a Mag5 which would give you 310GPH @ 4' head but I think its always better to have more pump on hand if needed in the future. You could also T off your intake side of the pump with a stronger pump and make a closed loop, thus utilizing more flow through your tank but only putting the limits on the overflow, this would require more plumbing on your behalf but would accomplish the best of both worlds. HTH

Gabe · 01-10-2003, 01:01 AM

I will explain with more detail. If my overflow is removing 300gph from my tank, and the return pump is pumping 500gph from the sump to the tank, than eventually the sump will run dry (no water will be in the sump). If the numbers were reversed (hypethetically speaking) and the overflow was removing 500gph and the return pump in the sump was pumping 300gph back to the main tank, than eventually the water level in the main tank will drop below the intake of the overflow box and the siphon would stop. Again to re-iterate, my overflow box removes 300gph from my tank, so idealy I would want a pump that returns 300gph of actuall water,( not what the pump says on the packaging) from the sump to the main tank. However this does not seem easy to accomplish because their are different variables. For instance the water has to travel verticaly threw the pvc over four feet from the sump to the tank so obviously I would need a pump that pumps more than 300gph in order to compensate for the distance and height that the water must travel. Now thats where the problem lies. How strong of a pump do I need so that the amount of water going into the tank is exactly the same as the water going out of the tank. Is their some sort of control valve I can purchase and attach to the PVC of the return pump? This must not be brain surgery and is possible to accomplish because it seems that this site is filled with experts all who own sumps. You guys must have figured it out, please enlighten me. Ninong, you have been here for a long time and seem to know oodles, whats your take on my problem? I hope I clarified my situation and question. Please help, thanks.

**kevinpo** · 01-10-2003, 08:29 AM

This is a simple problem (has to be I figured it out

). First let me correct one of the assumptions. An overflow box doesn't remove water from the tank. It just allows the water in the tank to return to the sump at the rate it which is pumped to the tank. If your pump is delivering more water than the overflow box can handle the water level rises in the tank as it does the overflow box will begin to accept more flow until it it is a maximum capacity then the tank will overflow.
Solution:
Install plastic ball /gate valve on delivery line (gate valves can be adjusted much more finely than ball valves).

In regards to too low of output from the pump. This only impacts the water level in the tank. For example overflow box is rated for 300 gph and pump is delivering 150 gph. The result:
There is half as much (50%) of the water flowing over the lip of the overflow box as it could handle. For example sake there would be 1/16" of water height over the lip of the overflow rather than 1/8" this would result in the tank water level being 1/16" lower. As you increase the flow to the tank the water level increases until you reach the 300 GPH level and now the tank water level is 1/16" higher than it was before.
One note on the ratings of the overflow boxes. They are rated to keep the water at acceptable levels in the tank. For example so the water doesn't hit the bottom of your center brace or glass covers. I have a 90 gal that has no center brace or covers and I use a pump that delivers about 20% more than the overflow is rated for. This results in the water level running quite high in the tank (right to the plastic ledge that holds the glass cover. So if I was using the covers the water would be hitting the bottom of them.

I hope this answers your question,

Regards,
Kevin
PS: Make sure your sump can handle the change in water level in the tank with both the pump on and off so in the event of a power outage you don't come home to find your sump overflowing on the floor.

01-09-2003, 09:41 PM	#1
Gabe Tenant Join Date: Aug 2000 Posts: 90	Help with water pump please Im adding a sump to my 50 gallon tank. Im using a cpr over flow that takes out 300 gallons per hour. My question is what kind of pump I should use(have decided upon internal for sure) to return the water back to the main tank, but more importantly how strong? I know I have to pump the water up over 4feet so i need a relatively strong one, but how do I balance the pump with the overflow. The dilema is this: if the pump is to strong it will drain the sump dry, if the pump isnt powerful enough, the cpr siphon will siphon itself dry because the water lever in the main tank will drop. Can somebody pleasssssse clarify matters with me. Any help would be appreciated, thanks.

01-10-2003, 12:49 AM	#3
scubadude Moderator Join Date: Nov 2000 Location: Wichita, Kansas Posts: 5,301	Hi Gabe :) Sounds like you have a couple of dilemas, First off a good pump for you would be something like a Mag7 at the minimum it produces 480GPH @ 4' head and you can put a ball valve on your output side and throttle it down to meet your Overflow demands. You could do a Mag5 which would give you 310GPH @ 4' head but I think its always better to have more pump on hand if needed in the future. You could also T off your intake side of the pump with a stronger pump and make a closed loop, thus utilizing more flow through your tank but only putting the limits on the overflow, this would require more plumbing on your behalf but would accomplish the best of both worlds. HTH

01-10-2003, 08:29 AM	#5
kevinpo Moderator Join Date: Oct 2001 Location: Spokane Valley WA Posts: 2,436	This is a simple problem (has to be I figured it out ). First let me correct one of the assumptions. An overflow box doesn't remove water from the tank. It just allows the water in the tank to return to the sump at the rate it which is pumped to the tank. If your pump is delivering more water than the overflow box can handle the water level rises in the tank as it does the overflow box will begin to accept more flow until it it is a maximum capacity then the tank will overflow. Solution: Install plastic ball /gate valve on delivery line (gate valves can be adjusted much more finely than ball valves). In regards to too low of output from the pump. This only impacts the water level in the tank. For example overflow box is rated for 300 gph and pump is delivering 150 gph. The result: There is half as much (50%) of the water flowing over the lip of the overflow box as it could handle. For example sake there would be 1/16" of water height over the lip of the overflow rather than 1/8" this would result in the tank water level being 1/16" lower. As you increase the flow to the tank the water level increases until you reach the 300 GPH level and now the tank water level is 1/16" higher than it was before. One note on the ratings of the overflow boxes. They are rated to keep the water at acceptable levels in the tank. For example so the water doesn't hit the bottom of your center brace or glass covers. I have a 90 gal that has no center brace or covers and I use a pump that delivers about 20% more than the overflow is rated for. This results in the water level running quite high in the tank (right to the plastic ledge that holds the glass cover. So if I was using the covers the water would be hitting the bottom of them. I hope this answers your question, Regards, Kevin PS: Make sure your sump can handle the change in water level in the tank with both the pump on and off so in the event of a power outage you don't come home to find your sump overflowing on the floor. __________________ SPSguy On - On

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01-09-2003, 10:30 PM	#2
Skunk Clown Tenant Join Date: Oct 2002 Location: This Giant World Posts: 89	ummm, i didnt really follow your thoughts. but let me stop you, i had........ yes had a cpr overflow, and i would rather have heaters and power heads hanging in my tank rather than one of these piles!

01-10-2003, 01:01 AM	#4
Gabe Tenant Join Date: Aug 2000 Posts: 90	I will explain with more detail. If my overflow is removing 300gph from my tank, and the return pump is pumping 500gph from the sump to the tank, than eventually the sump will run dry (no water will be in the sump). If the numbers were reversed (hypethetically speaking) and the overflow was removing 500gph and the return pump in the sump was pumping 300gph back to the main tank, than eventually the water level in the main tank will drop below the intake of the overflow box and the siphon would stop. Again to re-iterate, my overflow box removes 300gph from my tank, so idealy I would want a pump that returns 300gph of actuall water,( not what the pump says on the packaging) from the sump to the main tank. However this does not seem easy to accomplish because their are different variables. For instance the water has to travel verticaly threw the pvc over four feet from the sump to the tank so obviously I would need a pump that pumps more than 300gph in order to compensate for the distance and height that the water must travel. Now thats where the problem lies. How strong of a pump do I need so that the amount of water going into the tank is exactly the same as the water going out of the tank. Is their some sort of control valve I can purchase and attach to the PVC of the return pump? This must not be brain surgery and is possible to accomplish because it seems that this site is filled with experts all who own sumps. You guys must have figured it out, please enlighten me. Ninong, you have been here for a long time and seem to know oodles, whats your take on my problem? I hope I clarified my situation and question. Please help, thanks.

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