Hydor Bioflo Small Aerobic Filter

I recently purchased a Hydor Bioflo Small Aerobic Filter from Big Al’s. It looked like it could be a really good product. I have a problem with the top of my planted tank looking like like the water sitting in a dirty pot for 3 days… you know, that nasty looking scum on the top? Well, this product says that it “Eliminates white line effect and surface grease.” Sounds great, right? I am disapointed. While the “surface grease” has drecreased, it is still very much there. I gave it a chance. It came up lacking. Time to hack it to make it work better.

Hydor Bioflo Small Aerobic Filter sitting on the top of the water.

This is what the gizmo looks like in my tank. I think this is even what the water level should be from the photo on the box. Ok, maybe it is a little low. One of the problems with the filter I think, is that the water doesn’t actually flow through the sponge. It flows around it.

Hydor Bioflo Small Aerobic Filter peices and parts

Here are the major assemblies for the filter. The lower right piece is the outer housing which rotates around, spinning the filter that slips over it. The top center peice is the filter foam. The lower left assembly is the turbine and planetary gearing(that is the right name for this gear type, correct?).

Hydor Bioflo Small Aerobic Filter peices and parts

Here you can see that the housing has a very wide backplate. I think that the backplate is blocking much of the water flow through the sponge filter because it covers about half of the back surface area. The little round circles you can see in the reflection are molding lines.

Modified Hydor Bioflo Small Aerobic Filter to increase water flow

Here you can see the modifications I made to the backplane. I used the molding lines as a guide and drilled holes through the filter housing backplate. I am hoping that this will increase waterflow through the filter. I am going to give this modification about a week or two trial run and see if I can tell if it worked by examinging the filter foam.

Another modification that I thought of is modifying the shape of the teeth of the filter sponge. I think that makeing them cupped so that they actually cut into the water, encircling a small bit of the water surface before submersing will greatly increase the effectiveness of the “degreaseing” capabilities. Ths modification will also quickly submerge any floating food too – so it isn’t perfect (if it works as intended). I will wait and try this other modification after my 2 week trial on the existing modification. The larger version of the filter may be more effective as well.

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2 Replies to “Hydor Bioflo Small Aerobic Filter”

    1. I’d shelved the unit. My pump wasn’t enough flow to make it work reliably long term.
      I ended up continuously pouring water into the tank which does the trick nicely.

      I don’t think the holes really did much for me. I still think that cupping the ‘teeth’ would help. You want to surround a small amount of surface, and then bring it under. My current setups change too much in water height to make this effective.

      Maybe one of these days…

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