Sump level fluctuation question

[ilyad]

Hey everyone,

It's been a long time since I've had a tank and this time around I'm setting one up that has a sump. I've figured out the plumbing and all other aspects but noticed a small issue while doing a leak test...

After adjusting my water level in the return part of the sump, I let my tank run and it gets a small drop in the water level due to evaporation. Now I know this is normal. However, if I kill the return pump (as I would if I needed to do tank maintenance or other misc stuff) and then restart it again, the level in the sump will sit lower. This has happened on several occasions

I suspect this will be a problem because the level either doesn't go down far enough initially and the top off water wouldn't feed in enough (raising the salinity level) OR if the first is correct and the water drops below what it should be, there would be too much top off (lowering the salinity level).

Has anyone experienced this problem and can shed any light on what can be done?

Some specs:
25 gal display cube
5 gal sump (sump has 2 chambers - skimmer/in part and return/top off part separated by a chamber to trap bubbles)
Single return pump

Since the water capacity is so small the small change in the sump level would be noticeable when that happens.

Thanks in advance

 

[sleepydoc]

What kind of overflow do you have? There are not many places the water can go, since there are essentially only 4 chambers to your whole system: The main display area of your display tank, the overflow, the skimmer section of the sump and the return section.

The main display area overflows into the overflow, so the level and volume of the main display should remain constant. Likewise, the skimmer chamber overflows into the return section of the sump, so the skimmer section volume should remain constant. This only leaves 2 sections - the return section and the overflow. If the return section goes down, the water in the overflow section must go up.

My guess is there is something slightly affecting the flow from your overflow down to the sump, so the level in the overflow is increasing and making the return section drop.

 

[ericarenee]

What kind of overflow do you have? There are not many places the water can go, since there are essentially only 4 chambers to your whole system: The main display area of your display tank, the overflow, the skimmer section of the sump and the return section.

The main display area overflows into the overflow, so the level and volume of the main display should remain constant. Likewise, the skimmer chamber overflows into the return section of the sump, so the skimmer section volume should remain constant. This only leaves 2 sections - the return section and the overflow. If the return section goes down, the water in the overflow section must go up.

My guess is there is something slightly affecting the flow from your overflow down to the sump, so the level in the overflow is increasing and making the return section drop.

Air getting trapped somewhere in the plumbing comes to mind. Kinda like a bean animal starting up. Until its primed the Water in the external over flow box will rise well above its running level..

 

[ilyad]

I have a glass holes overflow rated up to 700gph (their normal kit) with a 1.5 inch pipe going down with a reverse durso at the end to minimize noise and bubbling in the sump.

As to your comment, that is what I though... I'll have to check the display to see if water level raises when that happens (causing it to drop in the sump), but I'm fairly confident that it's consistent. Otherwise I know that the skimmer section is constant with it being regulated by a baffle.

Is it possible that the return pump hosing can have air in the system either before or after the shot off and that doing that removes or adds it causing the change?

 

[ilyad]

Air getting trapped somewhere in the plumbing comes to mind. Kinda like a bean animal starting up. Until its primed the Water in the external over flow box will rise well above its running level..

That's what I'm thinking now - air trapped either in the downpipe or the return tubing. Any way to trouble shoot that minimize that from happening?

 

[ericarenee]

pictures of your plumbing and over flow boxes would help...

Short of that . If there is air in the pipes preventing water to return to its normal level.. The water would be in a over flow box or higher water level in the tank..

NOW The other side of that.. What is normally running you are getting air Bubbles building up inside a pipe someplace.. When you shut the system down and power pump back up its flushing that air out. Causing those pipes to be come full of water again...You would not see this slow build up of air being trapped . To you it would just look like precipitation and your ATO Would accommodate for it.

So again without pictures it would be hard to look and see any obvious issues.

If you have a OVER The top over flow box there is a chance air is getting trapped in the U Pipe.slowly over time . Then when you flush it (pump off and on) the water pushes the air out.. (Just one example)

Good Luck

 

[ilyad]

Here are some pictures of the filtration/plumbing parts

 

[Vinny Kreyling]

I never saw an overflow box with bubbles on the water, it always just flowed in a sheeting fashion. My suggestion would be to put a valve on the pump & slow the flow slowly until it straightens out.

 

[ilyad]

I never saw an overflow box with bubbles on the water, it always just flowed in a sheeting fashion. My suggestion would be to put a valve on the pump & slow the flow slowly until it straightens out.

I don't spot any bubbles on the water in the overflow. I think the netting/mesh to keep the gurgling down looks like it. Also the return pump is adjustable from 300-700gph at its outlet and currently turned all the way down.

 

[Vinny Kreyling]

A closer look & mesh it is, I never use it, take it out for as test run.

 

[sleepydoc]

Have you figured out where the level is varying?

It looks like you have a durso pipe on your overflow - you very well could have more water in the pipe itself, depending how the air inlet is tuned. Your overflow isn't very big. Even if it went from empty to full I wouldn't expect a huge change in the sump level. It's hard to tell how big the two are relative to each other, though.

 

[ilyad]

Sump level fluctuation question

Have you figured out where the level is varying?

It looks like you have a durso pipe on your overflow - you very well could have more water in the pipe itself, depending how the air inlet is tuned. Your overflow isn't very big. Even if it went from empty to full I wouldn't expect a huge change in the sump level. It's hard to tell how big the two are relative to each other, though.

Last time I checked the display stayed the same. So it looks like air in the piping/tubing or in the overflow. Can't see the overflow change since when I cut the pump, it drains down. The plumbing is 1.5 inches all the way through and the overflow is about 8x2 inches or so... I fear that it's sucking in air and that's fluctuating the flow rate over time.

The air inlet is pushed down and was rotated to minimize sound from the pipe. I'll try to mess around with it to see if there's a difference

 

[ericarenee]

what is that on the end of the Drain pipe.... Its hard to see how the Drain from tank is Connected to it..

I am guessing your problem is with that ....

 

[ilyad]

what is that on the end of the Drain pipe.... Its hard to see how the Drain from tank is Connected to it..

I am guessing your problem is with that ....

It's a reverse durso on the bottom to keep it from having too much noise/splash in the bottom of the drain.

This is a picture of one just like mine - too hard to squeeze in to take a descent picture of mine.

I hope that's not the cause since it's designed to purge the air out of the system.

 

[sleepydoc]

My guess is that the water is hiding in the pipe - 1.5" pipe can hold a reasonable amount, and it may be enough to explain the variation in a small return chamber.

What happens if you just let it run for a while?

 

[ilyad]

My guess is that the water is hiding in the pipe - 1.5" pipe can hold a reasonable amount, and it may be enough to explain the variation in a small return chamber.

What happens if you just let it run for a while?

I haven't done it long enough, but the times I did, it decreased at a constant rate until killing the pump - likely the actual evaporation amount.

I just hope I can get it squared away because I suspect it'll be an annoyance if I can't kill the return between water changes.

Perhaps someone has a recommendation on how to set up the plumbing that must come out of a 1.5 inch bulkhead that I can run on this tank minimizing air or fluctuation. I don't mind redoing the plumbing if there's a better version out there

 

[ilyad]

I spoke to a plumber the other day and was told if I am trying to do the air escape (reverse durso) in the sump, for best results, the y connector should be above the water level to allow maximum amount of air to escape. Will be trying to plumb this again and seeing if I get a better result

 

[sleepydoc]

Why the 'reverse' durso instead of a standard one? I have to wonder if that's the problem.

How much flow do you have? 1.5" pipe seems like overkill for a. 25 gallon tank.

 

[ilyad]

Why the 'reverse' durso instead of a standard one? I have to wonder if that's the problem.

How much flow do you have? 1.5" pipe seems like overkill for a. 25 gallon tank.

I'm not sure if that's what it's called... But this is the set up.

How does a standard one look? Also, the overflow is rated at 300-700gph. It's currently running on the lower end. Since I plan to run mostly sps, I wanted to have a high flow system. It may be that I should have gone with a smaller drain, but at this point the tank is already drilled with 1.5 inch so it doesn't leave me much options to downsize.

 

[Vinny Kreyling]

You can always reduce piping with reducer bushings.