Water Flow Problems

[carlyai]

I have two water pumps. One pumping water from a sump tank to fish tanks. The other pump pumping water from the fish tanks through a filter back to the sump tank.

The problem is it is extremely difficult to balance water flow into the fish tank and flow out of the fish tank because two pumps are used.

Hopefully a fix is to install an inverted P-trap on the fish tank drain so the water level in the tank will be at the same level as the bottom of the inverted P-trap. If the water starts to creep up in the fish tank it will overflow back to the sump.

What do you think? Going to work?

[Crossy]

I would control the tank - filter pump with a float switch.

 

Is it not possible to arrange a gravity return (via the P trap to draw from the tank bottom) to the sump and put the filter in the sump-tank feed?

 

[carlyai]

Thanks, ill have a think.

[carlyai]

11 minutes ago, carlyai said:

Thanks, ill have a think.

The filter needs to filter out all the solids from the fish tank before it gets to the sump. The sump also feeds grow beds. Problem is balacing the inflow from the sump pump with the outflow from the fish tanks. All this is setup. 

So the question is will my addition of the Upipe P-trap and overflow pipes stop the fish tanks from low water or too much water?

 

[Yellowtail]

It looks to me like having the pump between the tank-out and the filter in makes the trap useless. 

 

Were the filter open, fed from the top, drained from the bottom and at the same level as the height of the fish-tank you might make it work with gravity. 

 

 

 

[carlyai]

Gravity feed would have been the aim and only 1 sump pump, but I can't get the fish tanks high enough for flow thru the bead filter as water enters it from the bottom and leaves from the top.

If I had the fish tanks and filter in the green house I could do it, but I thought the fish tank water would get too hot so I installed them in an insulated room.

[Crossy]

OK, since we're stuck with having the second pump.

 

Organise a couple of float switches to sense too high (turns off the sump-tank pump) and too low (turns off the tank-filter pump) water in the tank. Adjust the flow on the filter pump to be "just about right".

 

Something like this 

https://www.lazada.co.th/products/17cm-length-liquid-water-level-sensor-stainless-steel-vertical-float-switch-i1113908594-s2550010352.html

You'll need relays / contactors to operate the pumps, put the floats in a length of PVC inside the tank to stop the fish bashing them.

[Yellowtail]

Assuming the filter is sealed, why would you not put the pump between the filter and the sump and save the wear on the pump?

 

[carlyai]

4 hours ago, Yellowtail said:

Assuming the filter is sealed, why would you not put the pump between the filter and the sump and save the wear on the pump?

 

I think you can but then the pump would be sucking from the filter not pumping to the filter. I think I saw something on the AST bead filter site that the pump is placed before the filter.  Also I can run my setup as 2 closed loops (hydroponic sump tank to grow beds and fish tanks through filter back to fish tanks) of all coupled.  I'm running it in 2 loops at the moment trying to sort out the 2 pumps issue. 

[Yellowtail]

4 minutes ago, carlyai said:

I think you can but then the pump would be sucking from the filter not pumping to the filter. I think I saw something on the AST bead filter site that the pump is placed before the filter.  Also I can run my setup as 2 closed loops (hydroponic sump tank to grow beds and fish tanks through filter back to fish tanks) of all coupled.  I'm running it in 2 loops at the moment trying to sort out the 2 pumps issue. 

 

Will the media in the grow beds not work and a biological filter for the fish tank? 

[carlyai]

5 hours ago, Crossy said:

OK, since we're stuck with having the second pump.

 

Organise a couple of float switches to sense too high (turns off the sump-tank pump) and too low (turns off the tank-filter pump) water in the tank. Adjust the flow on the filter pump to be "just about right".

 

Something like this 

https://www.lazada.co.th/products/17cm-length-liquid-water-level-sensor-stainless-steel-vertical-float-switch-i1113908594-s2550010352.html

You'll need relays / contactors to operate the pumps, put the floats in a length of PVC inside the tank to stop the fish bashing them.

I think this dynamic fix coupled with my static overflow and P-trap protection is a goer. Thanks.:)

[Crossy]

4 hours ago, Yellowtail said:

Assuming the filter is sealed, why would you not put the pump between the filter and the sump and save the wear on the pump?

 

Standard wisdom is that you pump in to a filter to reduce cavitation damage to the pump impeller if the filter becomes clogged. At the sizes we are looking at it's probably not a massive issue, but ...

[carlyai]

3 minutes ago, Yellowtail said:

 

Will the media in the grow beds not work and a biological filter for the fish tank? 

Yes  and the bubble beads as well. I seasoned the fish thru the filter and last records were TAN 0 and nitrates 150.

[carlyai]

7 minutes ago, carlyai said:

I think this dynamic fix coupled with my static overflow and P-trap protection is a goer. Thanks.:)

Crossy, I'd be looking at very small contractors as the pumps are less than 100 W. Can you get small current contractors  (may be wrong but I think the smallest I saw was 32A)?

[Yellowtail]

What is the p-trap protecting? The way it is configured now. would not the pump failing and leaking not drain the tank?

 

Is the filter located over the sump? If not, it leaking could drain the fish tank as well. 

[carlyai]

10 minutes ago, Crossy said:

 

Standard wisdom is that you pump in to a filter to reduce cavitation damage to the pump impeller if the filter becomes clogged. At the sizes we are looking at it's probably not a massive issue, but ...

I remember now with the pool pump I left a straight section of around a meter (think I only needed about .5 m) to reduce turbulence into the pump. The exact measurement is so many times the diameter of the pipe.

[carlyai]

5 minutes ago, Yellowtail said:

What is the p-trap protecting? The way it is configured now. would not the pump failing and leaking not drain the tank?

 

Is the filter located over the sump? If not, it leaking could drain the fish tank as well. 

My thinking is that (with one drain pump) if that fails the water in the tanks will stay at the same height as the bottom of the P-trap.

With the static and dynamic modifications I think it could be OK.

[Crossy]

6 minutes ago, carlyai said:

My thinking is that (with one drain pump) if that fails the water in the tanks will stay at the same height as the bottom of the P-trap.

With the static and dynamic modifications I think it could be OK.

 

I'm assuming the P has a vacuum breaker at the top of the loop to prevent syphoning the whole tank dry.

[Yellowtail]

I would raise the pump to whatever level I want the water to be in the tank should should it fail. 

12 hours ago, carlyai said:

Gravity feed would have been the aim and only 1 sump pump, but I can't get the fish tanks high enough for flow thru the bead filter as water enters it from the bottom and leaves from the top.

If I had the fish tanks and filter in the green house I could do it, but I thought the fish tank water would get too hot so I installed them in an insulated room.

 

Is the sump large enough to accommodate the filter such that you could get it low enough?

 

The pumps are really only 100 watts?

[maxpower]

Food for thought.

 

Our PCB wash tanks have inflow and outflow pumps which run continuously during process.

The outflow pump valve is restricted to X L/Min. The inflow pump is restricted to deliver less than the outflow.

 

This results in the tank slowly dropping its level if left in this condition.

 

To maintain level, a small electrically operated bypass valve sits in parallel with the inflow valve to increases inflow until a level switch is satisfied.

The control keeps the tank within approx 50mm level differential.  A high/low level alarm stops the pumps if control window is lost.

[sometimewoodworker]

1 hour ago, carlyai said:

Crossy, I'd be looking at very small contractors as the pumps are less than 100 W. Can you get small current contractors  (may be wrong but I think the smallest I saw was 32A)?

You can probably find small people to do work ???? but it think you are looking for contactors and as long as they’re rated to switch more than the power you need there is no problem 

[Crossy]

2 hours ago, carlyai said:

Crossy, I'd be looking at very small contractors as the pumps are less than 100 W. Can you get small current contractors  (may be wrong but I think the smallest I saw was 32A)?

 

At that power level look at relays rather than contactors. I'd use 12V DC to keep everything nice and simple and safe.

 

DO Ensure that you have a suppression diode (1N4007) across the relay coils (band on the diode to the + end of the coil) that are controlled by the level switch, the reed switches are not terribly robust.

[carlyai]

25 minutes ago, sometimewoodworker said:

You can probably find small people to do work ???? but it think you are looking for contactors and as long as they’re rated to switch more than the power you need there is no problem 

Yes, contactors. ???? So you don't need a thermal overload?

[carlyai]

I've just thought of a problem controlling the sump pump with a float level switch. The sump pump also pumps to the 4 grow beds that are on flood and drain using Bell Siphones. 

[carlyai]

Maybe the simplest work around is to re-engineer the fish tanks and make them 60 cm higher or 30 cm higher than the filter.

 

[Crossy]

If you set everything up correctly the sump pump should never go off unless the tank gets too high coz the filter pump isn't draining fast enough.

 

No need for thermal overloads on 100W pumps.

[Crossy]

4 minutes ago, carlyai said:

Maybe the simplest work around is to re-engineer the fish tanks and make them 60 cm higher or 30 cm higher than the filter.

 

If that means you can go gravity then sounds good. Gravity doesn't use any electricity.

[Yellowtail]

If you cut your p-trap at it's apex, (I assume this is the desired level for the fish tank water) will that not give you enough height to flow through the filter?

 

[carlyai]

29 minutes ago, Yellowtail said:

If you cut your p-trap at it's apex, (I assume this is the desired level for the fish tank water) will that not give you enough height to flow through the filter?

 

I think you need the fish tank water about 30 cm above the filter, so

In my case about 60cm and no real guarantee good flow thru the filter.

The P-trap has a screw threaded hole in the middle of the Ubend.

Anyway I've made an executive decision. ????

[carlyai]

I've made an executive decision. At the moment I am running a de-coupled system. The aquaculture fish are separate from the hydroponics. All I need to sort out is turning my filter backwash waste (gravity fed to a separate sump tank) into useable nutrients for the grow beds sump water. So I've abandoned the idea of two pumps controlling flows to the fish tanks.

I'll still put in the static and dynamic protection but for a de-coupled system and read up on mineralization tanks. I have heaps of airation agitation installed into the sump tanks already.

Thank you for all the valuable replies and I can start sleeping  again tonight. ????