Re: surface scum

[Thomas Barr <tcbiii at earthlink_net>]

> temp 29C
> PO4  0.0

You'll need some to get the NO3 uptake going.
Shoot for .2ppm to .5ppm. If all goes well up to .4ppm to 1.2ppm range.
If you add enough for .2ppm to .5ppm and it drops to zero the next day, add
about 2x more a week to those levels.

> Ca  40ppm
> Ammonia 0.0ppm
> nitrite 0.0ppm
> nitrate 5ppm/10ppm
> PH 6.8
> Kh 70ppm

Try lowering the pH to 6.6 with the CO2.

> gh 140ppm
> iron 0.0

Your likely weak on Traces and PO4.
Mix the PMDD stronger on the iron part or add separately.
Your getting enough NO3 and K but enough PO4 nor Traces.

> dose with PMDD
> tank contains 10 small discus ,10 ottos,5 clowns ,6 whiptails ,6 bristle nose
> cats ,6 Cory cats + 5 kulli loaches
> plants are growing great I have to trim once a week.
> we do 25% water changes twice a week with   60l of Ro + 40l of tap water

Feeding more will add more NH4 and not enough PO4.
Your going to need to add more traces and PO4 to get this tank going
stronger.

> thanking you
> Dean (outback OZ)

As far the algae, A suface skimmer will work great, it's likely a cyano
bacteria, they tend to float on the surface real well, a paper towel will
dab up most of it, a cup can skim off some etc, but good plant O2 production
will get things going well. PO4 limited tanks(very) often have slight
nuisance algae. Once the limitation is removed and you remove the algae
itself, it will not come back again.
Regards, 
Tom Barr