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Bruce

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I got a new tank the other day, the filter is a 4ft sump with an 8000l/h pump. With 2 standpipes feeding the water to the sump. How do I match the intake speed of the two pipes with the output of the pump? Usually the pump cannot match the intake speed and when I make the input more controlled the pump pushes it away too quickly. Help, it's driving me insane.

Bruce

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huh? which one is outflowing which? The pump or the standpipes?

with an 8000lph pump I hope those standpipes are at least 25mm ID each!

I usually set the tank up full to the top of the pipes, then fill the sump as this will be the total amount that can drain back during a blackout. Then you just turn on the pump & see where it equalises.

If the standpipes are too tall it'll overflow the tank, likewise if their flow rate is outmatched by the pump.

Can you please describe in more detail the setup & the problem? It kinda sounds like you aren't happy with the tank water level - which is simply adjusted with standpipe height

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Also a bypass on the return line might help. This way you will have water flowing straight from the pump back into the sump. The use of a tap will allow you to adjust the flow back into the tank. Not sure how well adjusting the height of the standpipes would work, there is usualy a limited range you can do this for. I think making them higher to decrease outflow is OK, just be carefull if you shorten them to try to increase flow, your sump may not be able to hold all the water when the pump stops.

Dave.

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The pipes are only 20mm thick. Attached is a picture of the tank and its setup. The S stands for stand pipes, O for output and P for pump. The standpipes have horizontal intake bars on the top with saw cuts for intake holes. The problem is that the amount of water coming into the sump is too much and the pump can't deal with all the water from the sump. As a consequence the sump starts filling up which takes water from the big tank which stops water flowing into the standpipes.

user posted image

Bruce

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I would do as dave said.

3 way tap the return pipe from the pump and pump the extra pressure from the pump back over the filter media. Reducing the load of water going back into the tank.

Or find a way to let more water back down standpipes.

From your graphic: Why aren't you just letting the water free fall (gravity) into the sump? It probably adds extra force having the water drop into an already existing body of water and out over the retaining glass. If I where you I would also put a 90 degree bend on the standpipe return just before it hits the sump and let the water fall into the return reseviour and into the secondary reseviour to stop the force.

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I don't want more water in the sump I want less. The pump can't move all the water out of the sump and so it starts filling up.

Bruce

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Might be a silly suggestion (I've never used a sump)

But can you use a cut off type valve thing on the standpipes? Like to slow the amount of water returning to the pump?

I'll go hide now.

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Don't...it's a good suggestion. I thought maybe smaller holes would reduce the flow rate but it didn't seem to have any real effect. I had it working fine this morning but then I added some more water and it stuffed up. I can't get it to work again now and I'm kicking myself angry.gif

Bruce

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Raise the level of the standpipes? Your problem is unique. 99% of the time it's the reverse that are giving people nightmares (tank overflowing..)

Mitch

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are both stand pipes at same height? is the overflow evenly distributed on both pipes?

dont run your sump, let the water level in the aquarium sit flush with the overflow, then turn your sump pump on and slowly add water to the aquarium.

if one of the standpipe is too high and you have water goin down from the higher pipe, it might cause the excess water.

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Bruce - the idea is the have gravity doing 1/2 the work for you. Two 20mm pipes should just about be getting overrun by that pump.

The idea is to have the standpipes about 20-30mm below where you want the waterline in the tank to be. Have the sump as full as you want it in a power out situation, then turn on the pump. This way the sump can NEVER be overfilled.

Also, the tank water level should not be able to drop below the top of the standpipes, ever. If it is & you are stopping flow with taps on the lines to the sump, are you sure the standpipes are properly sealed at the bulkheads?

edit: video on the way.....

edit2: It's 14mb MOV format, doh! dropping res & retrying

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I think the standpipes were at the wrong level, they were at the surface of the water. I am draining some water now so that I can cut them down. Also, if the power cuts won't the pump outlet just turn into a siphon and fill the sump us causing a flood?

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don't cut a thing yet, wait on!

how deep into the tank is your return line? they will act as a siphon

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so it stops at the top point of the standpipes, yes?

then you turn on the pump and somehow the sump fills more? dntknw.gif

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As seen in the diagram the water is about halfway across those horizontal intake bars. I think I will lower them though. I turn on the pump, remove the top of the standpipes, dip them in water to fill with water and get rid of airbubbles, replace them and then the sump gets too full. Maybe the standpipes are acting like siphons?

Bruce

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they shouldn't be, unless you have them going under water further.

you shouldn't have to take anything off, it should be set & forget in the tank. what exactly are you filling with water?

ps: here's two movies on one of my sump systems from the tank's point of view on & off. Right click & save as, viewable in Quicktime.

http://users.tpg.com.au/ajhinds/poweroff.mov

http://users.tpg.com.au/ajhinds/poweron.mov

The sump should have the most water when the pump is off, it should only have less when it is on.

Likewise the tank€ should have the least water with the pump of & the most with it on.

For some reason it sounds like you have the reverse happening.

Is you pump definately returning water to the tank? If you pull the return line out above water level to check if should gush out

edit: Try turning your slotted pipes upside down so the slots are at the top, no air bubbles or siphon then

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The pump is defianately working, you can see the water coming out. I will try turning the pipes so the slots are facing upwards. But then there may be air in the endcap area?

Bruce

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so what if there is? Why have those things anyway, only sick/dead fish will get sucked down a bare standpipe anyway.

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Bruce

Is the water coming back down the return line from the sump to the tank?

Josh

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I cannot leave the hole just bare...I tried it before and it made a whirlpool and start taking bubbles into the sump. There is no return on any of the pipes. Everything is flowing the way it should be. Just not at the right speed.

Bruce

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