[fsureefer]

I have a 400gph HOB filter that I am using with a piece of filter floss in my 40b. Out of the box, it did a great job of sucking stuff from the bottom, but wasn't skimming the surface at all. I tried phase 1 of surface skimmer modifications last week and it works kinda. It is sucking water from the surface, but also sucking air in a vortex, causing microbubbles. The 5/8'' tubing helps, but also impedes the water flow from the surface.

I was playing in sketchup this morning and came up with three designs that might work for a cheap PVC surface skimmer mod. I don't want to get a sump yet if I don't need to, although I might. For $5 in PVC, one of these has to be worth a shot. Note: the large piece of PVC will have slits cut into it similar to an overflow box, I couldn't get sketchup to cooperate.

#1- simplest from its current form. Still worried that it is going to suck air because of how the inlet is.

#2- might be the most effective option. Wondering though if the power goes out, will the pump be strong enough to get the surface skimmer going again? Would I need to add a check valve and air line to get a siphon started?

#3- not sure about this, the thought was that the 45 degree angle would break up the vortex, but I don't know.

What do y'all think? Pictures are its current inglorious form. It was plastic welded with a screwdriver and camp stove, definitely not a work of art.

 

[PhaneSoul]

I would just try to make it bigger. I took a pump off a hob filter, inverted it and added a box to it to surface skim, works great at the right water level, def think size or a valve is the key to what you (we) are doing here. Mine iz the same exact con ept but im just circulating the scum on top and you run it into a filter (i also have the option of attaching a filter sock to mine)

 

[fsureefer]

Can you elaborate? Make what bigger? The inlet pipe? (have a larger piece of PVC on top, a reducer, then the 3/4'' pipe?)

 

[PhaneSoul]

The part that actually draws in water from the surface. If you can get that part to retain water & not go dry while being turbulant i think it would work better. Maybe try a square instead of a circle, a cirlce seems like it would help create the vortex, my square doesnt create a vortex but due to tge turbid water in it and shallowness if the waterlevel drops too low it sucks air (no sump so water level in display fluctuates)

 

[fsureefer]

Thanks! Making the inlet larger did the trick. I used a 3''-1.25'' reducer, a bushing, and added another bend to the pipe to move it where I wanted it. No more sucking air and seems to be skimming much better.

 

[PhaneSoul]

Here is mine

If i rebuild it (which i will one day) ill design it so it has an inner box as well, the inner box will float with the water level while surface skimming