Sump level variation

ReefsandGeeks

ReefsandGeeks

New member
I'm new to having a sump and the water level during normal operation varies more than I thought it would. With my return pump flow set, the water level in my sump varies up or down probably 2 inches depending on when I check on it. I have an ATO in the sump, but occasionally the water level is a good 1-2 inches above the level sensor. Is that normal, or is there something going on in my tank? I don't know if that's an indicator of an issue with the return pump or the drain?
 
It sounds like something strange is going on, though I am not sure what. The water level should not CONSTANTLY fluctuate like that and should not rise about the ATO sensor/switch. There will be evaporation of course, so you may see a slight drop in water level, but this should be very minimal. Any small drop , usually about 1/8" will trigger the ATO and top it back up.

What ATO are you using and what size pump do you have for the ATO?
 
Yep.. Once the system is started up/stabilized (can take from a minute to a few minutes on average) the water level in the sump will reach a fixed level and should only go down due to evaporation..
If the water level is rising that indicates a problem
 
Alright, That's what I had figured. I'm not sure what too look at, but it would have to be with either the return pump or drain of the display as that's the only way I'd get more water in the sump. Maybe my return pump isn't consistently pumping at a constant flowrate? Not sure how I'd check on that one. My drain lines don't seem to be clogged.

I have a Tunze osmometer with the stock pump for top off water. Nothing super fancy, but seems to work well. Kicks on when level is low and off when high.
 
Type of overflow/drain setup?
Pictures maybe?
Does the water level in the overflow fluctuate too tracking sump level?

What pump?
Anything else "special" about it?
 
The overflow is just 2 bulkheads with "90s" on them, and some PVC turned upward at a slight angle until the tank water level was good. I don't have an overflow box in the tank.

I'm using a Mag 9.5 return pump for a 150 gallon tank. The return flow is choked with a ball valve. I know ball valves are touchy setting up, but the handle on it is pretty stiff and it hasn't been touched since set. The sump is an eshopps wet dry so no real baffles like a typical sump. There's only a single water level for the whole sump. I know not the best, but I'm looking into better options. If anything, that should make less variation in the sump because there's more square footage of area to absorb any extra water drained.

I'll try to get some pictures this evening.
 
A good thought, and it was pretty close actually, but I've moved it up a few days ago and still have the variation.

I have a couple pictures, but can't seem to figure out how to attach them.

I don't think it's the drains. They aren't getting a full siphon on either drain line.

Although I didn't think it was the return pump, is that still a likely candidate? I know ball valves aren't the best choice, but I was under the impression that once it's set it's set with either a ball valve or gate valve. The cross sectional area that the water flows through is constant in either case once set. Ball valves are just a lot more touchy when trying to find that sweet spot.

I also haven't cleaned out the mag pump. I intended on taking it apart once I got it (used, came with tank) but was short on time and knew it was working well since I used it to drain the tank previously and used it to circulate the tank during initial fill up. It's obviously pumping well, but maybe it needs cleaned to prevent variability in it's return flow?
 
I lifted the fill hose coming from the ATO resivour up and away from the water surface in the sump...

I think i may see where you're going with this. The end of the outlet from my ATO MAY be lower than the level of water in the ATO resivour. Perhaps it's slowly dribbling out when the pump isn't running.

I always had the resivour below the tank before, but now that I have a sump perhaps that should be a concern. I'll see what level the ATO is at and will adjust again. I'll set it up so the outlet of the hose is higher than the max height of the ATO resivour water level.
 
I had this happen and it took me a while to figure out too. Just fill up your ATO reservoir and trigger the pump. If it's still flowing when the pump turns off you've got a siphon. I solved this problem by simply not filling the reservoir as high since the container I was using was about the only shape I could use.
 
devastator007 said:
The overflow is just 2 bulkheads with "90s" on them, and some PVC turned upward at a slight angle until the tank water level was good. I don't have an overflow box in the tank.

I'm using a Mag 9.5 return pump for a 150 gallon tank. The return flow is choked with a ball valve. I know ball valves are touchy setting up, but the handle on it is pretty stiff and it hasn't been touched since set. The sump is an eshopps wet dry so no real baffles like a typical sump. There's only a single water level for the whole sump. I know not the best, but I'm looking into better options. If anything, that should make less variation in the sump because there's more square footage of area to absorb any extra water drained.

I'll try to get some pictures this evening.
Click to expand...

:fish1: Hi, why are you using a ball valve to restrict the water flow to the sump? :fish1:
 
Hmm, Checked last night and I'm not getting a siphon in the ATO. I will have to fill it up to the top and try again as it was only about 2/3 full when I checked. My sump water level was about 1.25" above the shut off point for the ATO in the sump, so seems like something is still going on though.

I'm using a ball valve because it's all I was able to find locally when setting up the tank. I plan on adding in a gate valve to the return line at a later point and will simply open the ball valve when I have the gate valve installed. This may be a little while now due to some unexpected recent medical bills.
 
Green Chromis said:
:fish1: Hi, why are you using a ball valve to restrict the water flow to the sump? :fish1:
Click to expand...


Restricting flow in the drain pipe is usually the only way to guarantee a siphon in the line. Otherwise too much water flows and your siphon breaks because it starts to suck in air.


It can work with a ball valve. That's what I use in my display. I also had to add a valve to the return pump. It took a bit of tinkering, but the system is very stable now.
 
Green Chromis said:
:fish1: Hi, why are you using a ball valve to restrict the water flow to the sump? :fish1:
Click to expand...

By return flow, I mean flow from my sump to the display tank. not overflow from the display to the sump. Not sure if I said that in a misleading way. There is no restriction on my return lines.
 
devastator007 said:
By return flow, I mean flow from my sump to the display tank. not overflow from the display to the sump. Not sure if I said that in a misleading way. There is no restriction on my return lines.
Click to expand...

:fish1: Ok, thanks, so you have to big of a pump for your overflow, I'm guessing. :fish1:
 
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