i'm stumped

[MKLKT]

If the water level is rising in the top there is either a clog of some kind or the return pump is pumping faster than the drain is channeling somehow.

What are the dimensions of the plumbing and what size return pump are you running?

[monocus]

my drain is a 2" stockman and my pump is a bayside poseidon ps2 going into an oceans motion wavemaker with 1"return lines(4).my drain is clear as i just inspected it today.i have actually turned down the flow leading to my pump(ball valve)the thing is it doesn't happen all the time.maybe 2-3 times a month for a day or two

[emerald crab]

You might have bacterial build-up on your drain pipes. Under certain conditions, like carbon dosing, etc. the bacterial mat swells reducing the available section of the pipe, usual somewhere were you already have a flow restrictor.

[monocus]

drain is clean-i put my aquamedic scrub brush down last week and cleaned the lower drain as well

[reefwars]

Originally Posted by monocus

drain is clean-i put my aquamedic scrub brush down last week and cleaned the lower drain as well

just a shot in the dark but is it possible your pumps pumping out more than it should at times?? maybe somethings in its messed up

[monocus]

no idea-only happens 2-3 times a month.i was thinking it was some type of vapor lock

[ScubaSteve]

I used the same pump in my experimental set-up at work. I've noticed the flow rate can vary. For me what happens is that small air bubbles get into and build up int the pump which reduces output. Then after a while I get a big bunch of bubbles that comes out of the pump and the Flow rate bounces back up again. This has been throwing my automatic control because the control system tunes itself to deal with the gradual decrease in flow and is then thrown out of whack when there is an instantaneous change in flow rate as the bubble leaves.

Do you hear your pump getting noisy at all?