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hello. i'm writing this post on behalf of some customers i have at the store where i work. they have been fighting a losing battle against a growth that they assume is algae, and i couldn't determine a solution, so i figured i'd turn to the experts for advice! : )

anyhow, as i mentioned, the algae is medium greenish brown, and is growing on the glass, rocks, etc... they have completely removed it a few times, only to have it grow back very rapidly.

obviously, the first cause we ruled out was poor water quality. all their parameters (nitrite, nitrate, ammonia, pH) are normal/acceptable. i didn't, however, test for phosphates or iron... is this a potential cause? just as an aside, they don't use any plant fertilizer and everything they have in the tank was purchased for use in aquariums.

i also ruled out excessive light as a factor. they have their lights on a timer to be on no more than 8 hours a day, and the tank does not get direct sunlight.

their tank is not overstocked, either.

i thought perhaps they are dealing with some sort of cyanobacteria, but isn't that usually dark green/black? also, they did mention that they need to actually scrub to get the algae off. it doesn't come off easily.

so...... are you as stumped as me? or is there something i've missed? any other parameters i should be checking? anything they can do to help get rid of their mystery growth?

any and all advice is appreciated. thanks in advance!

High phosphates could definately be a cause, be sure to test for them...

What's the texture of it? Is it stringy? or does it grow in sheets? Fuzzy?

How many watts of what kind of lights are in the tank, and how big is the tank?

And what do you mean by normal/acceptable parameters? Everybody has a different definition, so exact numbers would be a big help there.

It possibly could be cyano, but I doubt it. I'm thinking it's some sort of a green slime algae, but I'm not sure...

HTH

Waffle is thinking of "green slime". If the tanks are relatively new set-ups, the algae is likely to be diatom algae. The following is from "Freshwater Aquariums":

Brown Algae

Other Names: Gravel algae, Silica algae

Color: Brown

Appearance: Begins as brown patches on the gravel and/or glass, then rapidly coats most surfaces of the aquarium with a thin, dark brown coating that is easily removed. Unlike blue-green/slime algae, it does not come off in large slimy sheets.

o Cause: Excess silicates & nitrates
o Inadequate light
o Low oxygen levels

Brown algae is a common occurrence in a newly set up aquarium. It is generally caused by too little light, an excess of silicates, an abundance of nutrients, and too little oxygen. Silicates can build up through tap water that is high in silicic acid, and silicates that leech from some types of substrates.

Cure:
o Wipe off surfaces & vaccine gravel well
o Increase the lighting
o Stock a plecostomus or several otocinclus

This type of algae does not adhere strongly to the tank surfaces, and is easily wiped away. Vacuuming the gravel with a siphon will quickly remove coatings from the substrate. Increasing the lighting will inhibit regrowth of brown algae. As a new tank matures brown algae is often eliminated naturally by plants and green algae competing for nutrients.

Some suckermouth catfish will readily eat brown algae, most notably plecostomus and otocinclus. If the problem is due to high silicates in the water, and the brown algae persists, a special silicate absorbing resin can be used in the filter.

Prevention:
# Use of RO water
# Regular water changes
# Regular aquarium cleaning
# Good lighting

As with any algae, keeping the tank clean and performing regular water changes is one of the best preventative measures. Unfortunately it is still possible to get algae in spite of regular maintenance, especially in a newly established aquarium. Prompt attention to sudden algae growth will prevent more serious problems.

My experience has been that the silicate type algae will recur in mature set-ups if maintenance declines. Unlike other algae types, do lengthen the lighting period and increase light intensity as you clean filters, vacuum gravel and do water changes.



__________
"To steal ideas from one person is plagiarism; to steal from many is research."
researched from Steven Wright

hi guys! thanks for the advice insofar.

as far as i know, the tank is about 30G, and is equipped with just standard flourescent lighting (probably less than 2W/gallon). the customers mentioned, i believe, that they have the lights on for less than 8 hours a day, and since the algae issue, have reduced the duration even more.

i think the tank is also mature... and as i mentioned, the water quality is fine (ammonia 0, nitrite 0, nitrate, 20ppm, pH about 7.2). the customers seem educated about aquarium care and maitenance, and perform regular water changes/tests.

also... the thing that stumps me is that the algae does not come off easily, as mentioned in the article provided above. they said that they have to scrub it with a toothbrush to get it off.

any other ideas?
thanks again!