Surface skim - not happening

[bigworm175]

I was basically given ($20) an Eshopps overflow box. It's the 1000 gph. It leaves way too much film on the surface. It pulls water to the sump, just not from the surface of the DT. I know these aren't the best overflow boxes but am I doing something wrong?

 

[sjm817]

For an overflow to surface skim, the water must "fall" into the overflow. The water level inside the overflow box must be lower than the outside. Is the water level inside the overflow box below the bottom of the teeth?

 

[bigworm175]

If I let the water level in the inside box get that low I have to turn my return pump way down and I will get very low flow between sump and DT. My pump is 1000 but with the 2.5-3 ft. head to the tank it can't be at the overflow's max. ???

 

[sjm817]

If you max out the overflows capacity, the level in the box will rise like that. The Eshopps have a very shallow box which doesn't help. You need to reduce the flow so the water level is just below the bottom of the teeth. You will see an immediate improvement in surface skimming.

 

[luther1200]

You may be trying to push to much water through it. And not letting the water fall over the ledge properly.

 

[bigworm175]

Thanks. That is probably it. I was unaware that the max doesn't allow for skimming.

 

[sjm817]

The GPH "ratings" of most overflows are optimistic to say the least.

 

[bigworm175]

Kind of like the skimmers I guess. We need a truth in labeling law for aquarium equipment or something.