John,

Algae killers only address the symptom and don't get to the heart of
the problem.

Do you know any of the other important water chemistry numbers like
ammonia, nitrite, nitrate, general hardness (gH) and alkalinity (kH)?
My guess is that with a pH in the low 7s if your alkalinity (kH) is
low, there is little CO2 there for the higher plants, so the algae get
the upper hand. If you have stock lighting, a single flourescent tube
is pretty much standard issue, it may not be enough light for the
plants to thrive. If you're low on light and CO2 that explains why the
plants aren't doing well.

You may also need to step up water changing and maintain the filter so
that nitrates are reduced.

Lilly

(marcos) wrote in message news:

So I've wasted my money on algaecides then but anyway i bought them
nearly a year ago. I have 3 plants: 2 r supposed 2b tropical and 1
coldwater - java fern. lights on 8 hrs a day. 3 twin-tailed goldfish
in a 70 liter tank (don't no exact measurements). dunno about the
water hardness. pH is 7-7.5, temp 20c. why am I keeping such a low
temp?? cos ive always known GF 2b coldwater fish. so shud i plug in my
tank heater then n what temp? ok thnx
john