[boba40]

i just filled my tank with about 72 gallons of water along with 90 lbs. sand.it is a 90 gallon tank
i have an eshopps sump and a mag pump model 9.5..it seems like the pump is pumping too much water that the drain can't keep up.the water in the drain/return compartment is fluctuating about an inch or so it sounds like a toilette flushing.i am open to all suggestions.oh yeah,i do have a gate valve on the return and it is almost closed all of the way

[carym]

How many drain lines and what size are they?

[boba40]

there is one drain line that is 1 inch in diameter.that is the inside diameter of the fitting at the bulkhead also.the drain line is a straight drop from the bottom of the tank to the drain compartment in the sump

[Jer77]

A good rule of thumb is that a 1'' diameter drain can handle up to 600gph. So your gonna need more drains or a larger one. The flow into your tank probably is less than 950gph because of head pressure, but it is definitely more than 600gph which is causing your problems. For a 90g tank the pump is a good size so don't get a smaller pump, just get a larger drain.

[NATIVEVAMAN]

The problem with changing the drain in a drilled tank is that the hole is made for a specific size bulkhead which is made for a specific size pipe.The problem could be one of two things,you need more water or you need a smaller pump.Add two gallons of water to the tank,if it keeps fluctuating then its the pump.I am betting on low water.

[msbdiving]

Your flow doesn't have to be just from the pump. Get a smaller pump and put a powerhead in to make up for the flow. This way you will be able to better direct the current.

[boba40]

thanks guys.after consulting with the lfs,they had me restrict the flow on the return by using the ball valve that i had installed.i do have two koralia 850 gph power heads in the tank with plans for a third when i get som live rock in.nativeaman,i understand your thoughts on the drain.the bulkhead is an inch i.d. fitting if i am not mistaken even if i go to a larger pipe the flow would stay close to the same due to the restriction of passing through the bulkhead.

[boba40]

also i forgot to mentio that my drain pipe does go into the sump and is approx .two inches below the water level.could there be backpressure against th incoming water?

[icu-travis]

i had the same problem with my overflows. drove my wife crazy could not even hear the tv in the livin room it was so load. i cut a piece of airline long enough to go about 4 inches down inside the tube then ran it up the back of my canopy and secured it. it acts like a venturi and mixes the air lower in the tube so you eliminate that growling noise all together plus dont forget that the open end of the tube has to be above the water level or when the power goes off it will turn into a siphon and drain your tank.