I have a protien build up (white scum) on the top of my tank if I do not get enough surface aggitation. If I run an aerator at night it fixes this but I do not like to because it causes my ph to go up over night by .3 to .4 points. Any ideas on how to control this other than with mollies which I have no desire to own.

Is there a reason why youre uncomfortable with your pH pending? I bet your fish doesnt care.. and if youre worried about CO2 just have it go on 1 hour prior the lightning does.
Otherwise, removing it manually with a piece of newspaper works.

I tried a few different methods of removing surface scum in some nanos I had. I ultimately found that running O2 at night on a timer was the easiest and best method of eliminating surface scum. There was also an unanticipated side effect...my water is clearer.

These nanos are pressurized Co2 with glass diffusers and powerheads with sponge blocks for circulation/filtration/Co2 blasting.

Changes in PH are not as important as changes in TDS (total dissolved solids) because of fish osmotic pressure. When fish start dying people pull out their test kits. The most common test kit is the PH test kit. People use it and notice a marked change in PH, so they blame the losses on a ph shift. Since most people can't test for changes is TDS levels, they don't realize that the TDS changes affected the PH. PH is all they can see so they don't understand the underlying cause.

I'm definitely not saying PH isn't important at all. I'm saying PH is often the red-headed step child and sometimes takes the blame for things that it wasn't responsible for.

I virtually never have surface scum:

Large water changes, active plant growth=> high O2 levels=> high bacterial growth rates which consume and decompose the protein and lipids on the water 's surface.

When plant growth is poor, the plants leak or proteins and lipids, the bacteria do not grow as fast, algae pops up, then you get scum.

Seen it a few times, took plant cuttings/leaves etc, this produced a nice oily layer.

Try this: put some excess plants in a bucket and leave it for a few days, you'll see an oily layer form.

As the plant rot/leach, the oil/promtins/lipids come out.

If you take a very actively growing tank, the O2 should be high enough to remove it and frequent waters with this will remove it.

Generally it's a sign I can further maximize my CO2 more when I see it.

Regards,
Tom Barr

Thanks everyone for the responses. I plan on totally redoing my tank within the next month and hope to have more plants and more growth. Hopefully the scum will go away. For the moment I will plug the aeraot back in.

Aeration does not hurt.
But a powerhead agitating the surface does a better job.

Fluff's up any settling on the leaves etc.
I do this anyway every 3-7 days with my hand.


Regards,
Tom Barr