Help Our Sump Doesn't Work!

[sarahw20000]

Okay lots of info to take in, the pipe size is all 40mm(as stated at top of post) and there are no restrictions on the flow at the mo because all the valves are open.

We took out the last divider between the pump and heater section so the pump chamber is now bigger, it helped slightly but not enough.

The standpipe is mostly out of water, when the water level does rise above it, it then drains and makes a sucking noise.


We've filled the tank and sump as high as it can go without the sump flooding in the event of a powercut.

And all of this has been tried with no media, we're trying to get the basics to work first and then we'll worry about the media.

I will get some pics but i can't post them on here coz i don't know how, i could e-mail then to some one to post?

 

[Fatty]

Ok,

this is my theory, basically I reckon the sump is just not tall enough for the needed amount of water.

because>

The length of the overflow (exposed to the surface of the water), determines how high the main tank water rises depending on flow to go through/over the overflow. ie., if you have a tiny L shape overflow in the corner then you are going to get an 1" or 2" head of water, but if for example the overflow runs across the whole back of the tank (just an extreme example) the head of water would be very small say 5mm. (by the sounds of it I don't think the standpipe has a capacity problem, perhaps just too small an overflow causing a large head of water)

In a power cut the complete head of water needs to drain into the sump, if the overflow were large this would result in only a 5mm head of water trickling into the sump, .. but if the overflow was small that's a much larger head of water, i.e, in a big tank quite alot over the large surface.

Solution is to either make the overflow weir surface (filter comb part) bigger, so has less of a head of water or get a taller sump.

I think it makes sense!!

 

[sarahw20000]

Ok,

this is my theory, basically I reckon the sump is just not tall enough for the needed amount of water.

because>

The length of the overflow (exposed to the surface of the water), determines how high the main tank water rises depending on flow to go through/over the overflow. ie., if you have a tiny L shape overflow in the corner then you are going to get an 1" or 2" head of water, but if for example the overflow runs across the whole back of the tank (just an extreme example) the head of water would be very small say 5mm. (by the sounds of it I don't think the standpipe has a capacity problem, perhaps just too small an overflow causing a large head of water)

In a power cut the complete head of water needs to drain into the sump, if the overflow were large this would result in only a 5mm head of water trickling into the sump, .. but if the overflow was small that's a much larger head of water, i.e, in a big tank quite alot over the large surface.

Solution is to either make the overflow weir surface (filter comb part) bigger, so has less of a head of water or get a taller sump.

I think it makes sense!!

Okay that does make sense but when we decided on sizes i calculated the amount of water that the sump would need to take in the event of a powercut and the sump has plenty of room for that. The head of water is 1/2 an inch multiplied by the footprint of the tank (83" x 20") = 830 cubic inches of water

To this I added the contents of the weir above the standpipe which is 6"x6"x10" =360
=total of 1190 cubic inches of water

The sump footprint is 12"x36" and the dividers are 10" high leaving 7" of height so 3024 cubic inches of space which is more than enough room for the excess water.

Please correct me if i've worked this out wrong, maybe thats the problem - my maths!

 

[Fatty]

To this I added the contents of the weir above the standpipe which is 6"x6"x10" =360
=total of 1190 cubic inches of water

Ok,

Firstly I'm confused as to why there is a body of water above the standpipe? If the top of the standpipe is 10" underwater, this means that the standpipe is not large enough to cope with the flow. The top of the standpipe should be level with the top of the water in the weir (if not slightly above).

If this is not the case then I have just mis-understood.

If the standpipe is large enough in diameter then try the following.

1. Turn off the sump pump and let the water levels settle.

2. Top the sump up to the maximum it can possibly hold.

3. Turn the sump pump back on (have no restrictions anywhere, apart from throttling the pump if desired). And wait.

If the sump pump chamber still runs dry and the standpipe is coping with the flow, then you simply do not have a big enough sump or a big enough overflow comb (ie. to reduce the 1/2" head on the main tank).

If you changed the pump for a smaller one, or throttle back the existing one this will solve the above problem too.

 

[SkiFletch]

Sarah, I might be able to help you but I'll need pics, go ahead and email them to me at skifletch@gmail.com and I'll host them up for ya. Take as many pics of the weir/standpipe and the pipework as you can. That email account has virtually unlimited capacity with 10mb per email so dont seend to many .bmp pictrues in one go, break em up

I've got some ideas but I'd rather see what you've got before I go confusing you further

 

[sarahw20000]

To this I added the contents of the weir above the standpipe which is 6"x6"x10" =360
=total of 1190 cubic inches of water

Ok,

Firstly I'm confused as to why there is a body of water above the standpipe? If the top of the standpipe is 10" underwater, this means that the standpipe is not large enough to cope with the flow. The top of the standpipe should be level with the top of the water in the weir (if not slightly above).

If this is not the case then I have just mis-understood.

If the standpipe is large enough in diameter then try the following.

1. Turn off the sump pump and let the water levels settle.

2. Top the sump up to the maximum it can possibly hold.

3. Turn the sump pump back on (have no restrictions anywhere, apart from throttling the pump if desired). And wait.

If the sump pump chamber still runs dry and the standpipe is coping with the flow, then you simply do not have a big enough sump or a big enough overflow comb (ie. to reduce the 1/2" head on the main tank).

If you changed the pump for a smaller one, or throttle back the existing one this will solve the above problem too.

There isn't normally water above the standpipe, i just calculated how much the contents of the weir was incase the pump turned off (any water under the standpipe wouldn't matter obviously because it can't suck it up)

Skifletch- i've e-mailed you some pics but there will be more in a few days when we've fiddled a bit more with the new bits we've ordered. Thanks!

 

[SkiFletch]

Thanks for the pics sarah, I'll get em posted later tonight since I dont have the resources here at work that I do at home . Check for them when you wake up in the morning

 

[SkiFletch]

A quick addition sarah. As I look at it now I see 3 potential problems. First off, your standpipe itself is WAY too high. You want to shorten the tube so that water cascades over the edge of the internal box and down to where the standpipe takes it away . If water cant cascade over the internal box, you loose some potential there.

Second possible problem is that your bubble walls go very close to the bottom of the sump. I'd have left another 1/2" in addition to what you have there just to be safe. I'm not sure how much it will affect your overall flow having them so close to the bottom, and it might not be a problem overall, but if all else fails thats a good place to look.

Finally, your final compartment with the pump is very small. You can get around this by filling the sump up above that dashed line you have there before you start it running. That gives you a lot of extra water volume for the pump to draw off of.

Also, although it has nothing to do with your problem, you should have a pipe extending about halfway downward into the first chamber there from your sump inlet. That way you wont hear water trickling all day long and have to go to the bathroom every 5 minutes I have thoughts about your pipework too, but that'll have to wait till I get home to edit the pictures and show you what I mean

 

[SkiFletch]

Ok, I've made corrections in Red and Green so you can see where you should be headed here, hope these make sense

First up, the shot of the standpipe. The correction shows it should be a little bit shorter than what you have:

Then the full tank shot, again showing where your standpipe should stand:

Then, a shot of the sump itself illustrating how the overflow line should be extended down below the water level. Also the green line indicates where you should keep the water to prevent draining the pump area.

Finally, a shot of the return pipe to illustrate what andywg said... Put a T in that line with a ball valve on that T back to the sump so that you can control the flow of water back into it that way as opposed to restricting the output with a ball valve which is bad for the pump.

Edit: Do you have a check valve on the return line from the sump to the display? Cause if not, you'll risk siphoning back and draining the display into the sump...

 

[mr.dark-saint]

Looks to me like the sump is rigged "backwards". Where the pump is should be the first chamber from the over flow should be. Since, the water has to rise high enough before it gets pushed back through the system (no wonder the thing runs dry).

As for the stand pipe in the over flow I'd go with out it and larger PVC would ease the flow restrictions. The 1/2" looking pipes has to travel far in that small opening. If it were me I'd move the "sump" closer to the over flow and re-pipe it with a bigger pipe. If this is not possible without making the drill hole larger use a reducer fitting. Like a 1/2" to a 3/4" or 1/2" to 1" this way there will be a slight bottle neck but it'll be less restrictive than going through 1/2" for three feet.

 

[sarahw20000]

Ski fletch thanks for all your ideas but unfortunatly none of them are relevant due to my un-updated pics.

Firstly what you are calling the standpipe is actually the return pipe, it is a bit shorter now so the water doesn't spray over the surface and there is now a non return valve on it.

The standpipe in now in the weir with the intake about 8 inches down.

In the sump there is a longer bit of pipe that screws on to make it quieter.

And we took out the divider closest to the pump to make the chamber bigger.

Mr Dark Saint- the pump is in the last chamber because thats the return pipe you see in the pic not the standpipe, and the pipes are all 40mm which hopefully is big enough.

Thanks for all your comments guys, i've got some more updated pics which i'm e-mailing to you right now Skifletch and we put a ball valve on the return pipework today to slow the pump down. The good news is that it really helps and everything basically works now, we're just waiting on the bits to put the t-piece in for the pump chamber and then we won't have to restrict the pump quite so much.

With the new ball valve in the pump chamber doesn't drain anymore which means the ball valve on the inlet pipes can be closed more which means the weir doesn't drain itself too quick, which is all brilliant but is it normal for the level of the water in the weir to gradually go up and down?

On another note let me know what you think of the look of the tank in the new pics?

Thanks!!!!

 

[SkiFletch]

Got your mail sarah, I'll post up the pics in a little bit. Gotta go watch my Sabres play

 

[Fatty]

Sarah,

Good to hear it's finally working, and yes it is normal for the water in the weir to go up and down. Again, aslong as the standpipe is never submerged completely and still draws in air.

Look up durso standpipe, I have fitted one of these with an air valve in the top for slight adjustments, the durso makes the noise much less by steadying the water at one level. So there is no big gulping catchup, if you see what I mean.

And if you don't want to go to the hassle of making the durso you can always try suspending a short piece of large airline tubing in the top of the standpipe, the water still goes up and down but will make it quieter.

 

[SkiFletch]

Amen to that Fatty, she actually made a Durso . Here's the updated pics:

Looks better now Sarah. Once you get that T fitting and valve in there to turn the return pump down a bit without angering it too much you should be good to go

 

[sarahw20000]

Hello again
We've been waiting for some pipe to finish it off which we got yesterday morning and we set it up today and it's working!!! We keep anxiously checking the level of the water in the sump to make sure it's all still stabilised but it seems good at the mo and quite quiet although that should get better when i've built a hood for it. If all goes to plan we'll be getting a 9" common plec from betta aquatics!

I can't wait to have something to look at in there!!

Thanks again for everyones help on this and i will get some final pics when the fish are in.