DT overflowed

Hi 3reefers! I yet have another problem :/ Today I noticed, that my sump's water level was low, so I topped it off (my ATO is currently being shipped here after being serviced). Five minutes later, I noticed air jets coming out of my nozzles, so I hurried to top off my sump with RO water again, but by the time I got to it, the problem had regulated itself. The water level in the sump jumps from not enough water, to just above where I like to keep it. I turned off my return pump so I could sort out the problem, but I thought I'd post here to see if anyone may have a solution. When the pump was left on, the DT's water level could shift to the height of the top of the corner overflow (when the sump's water level was low). I'll post back if I find anything, but suggestions are welcome! If it helps at all, I attached a picture of my tank I drew up for a previous problem. Thanks again!

 

The only thing I can think of (and this happened to me on my current set up) is that not enough air is allowed to get into the drain from the tank and it starts to back up (e.g. not let though as much water). When this happens the sump level lowers and the tank level rises. Then when the pressure gets high enough it flushes and the sump level goes back up again.

Very annoying to be sure. I have a very unconventional drain so what I did may not work for you, but I added an air vent at the top of the drain pipe and it solved the problem.

 

I'm not 100% what you mean by "air vent", but what I think you mean is a hole in the cap of the PVC... which is what I did, seen below.

 

That hole may be a bit small. If it's not big enough then you create a suction in the drain that will back it up like I mentioned below. The vent I have is quite different, but you shouldn't need that. You might want to bore out that hole a bit.

EDIT: Your water flow and the height of the drop to the sump determines how much air needs to get into the drain to ensure smooth flow.

 

I'm thinking that that might fix it, but I'm still unsure as to why that would be the problem, since this only started happening today.

 

I had the same problem with mine. Thought it was fine for a while but then I just noticed the swing. Did a bunch of things but nothing really helped.
I ended up drilling 2 more 3/8" holes in each of my stockmans and now it's smooth sailing. I agree with rocketman. I think if you drill a hole and see if it helps.

 

Yeah, but drains can be temperamental depending on the design and exact build. Something gets lodged in a pump's impeller, slows the flow by like a couple percent and it's just enough to make the drains start acting weird.

I still get nasty gurgling that afflicts me every once in a while. Everything is fine then for like 20 minutes the drain starts slurping bad. Then it goes back to normal for the next three weeks.

 

Hmm..... I drilled another hole in the cap and the DT still fills up too high... I tried taking the cap off completely, but that still doesn't solve my problem

 

Next questions...

How big is the drain hole in the overflow?

How big is your drain pipe from the overflow to your sump?

Have you checked for snails?

Have you tried slowing the return flow at all?

 

One more:

How long was the tank going before this started?