Re: surface extractor

>DIONIGI MALADORNO "rnisd0::mrgate::a1::maladord"@rnisd0.DNET.roche.com
>>I did not know that plants produce floating film and scum. Can anyone
>>explain in simple terms how that happens? I have mixed floating plants
>>(duckweed, frogbite and Pistia: did I spell them right?)in my 180 gal. tank,
>>in addition to a good number of submersed plants (mostly swords, Cabomba and
>>Crinum). I normally have little or no floating film despite a medium fish
>>load (no surface extractor) and I thought that the root system of the
>>floating plants absorbed it in some way. Does this make sense?

I have this "scum" problem and it wasn't there when I had lots of Salvinia
and water sprite, however, I also upped my iron about the same time I got
rid of most of the floating plants. Thread algae appeared along with the
scum and I think it is all due to too much iron. I've cut off the
fertilizer to lower the iron and waiting to see what happens.
>I've noticed the same thing, if I have at least half the surface of
>the water covered with floating plants it stays crystal clear. I don't
>have an explanation why that happens, though, maybe somebody else
>knows anything about this? This surface scum is very frustrating. I've
>read that breaking the surface film with an outside power filter makes
>it go away, I've been filtering my heavily planted 10 gal for about 2
>mos now with an Aquaclear mini which for the 1st mo was on full flow
>(before I started adding CO2) and and I haven't noticed any
>improvement. The Dennerle book says it's caused by iron consuming
>bacteria which indicates that there is enough iron in the water and
>that it dissapeares on it's own after a short while ?! Did anybody
>notice this to happen ?

I also agitated the surface for awhile -- it made no difference. So what is
this stuff? I've been told it's "a protein layer" and "iron eating
bacteria". So which is it? Why is it there? and does one have to get a
protein skimmer to remove it?