GD Taylor wrote,
One of my platys has got white spot and I have no idea what
the best way to treat the tank ...........

Skin and gill protozoans such as ich (white spot), velvet, costia, etc
will not tolerate temperatures above 85º. Trouble is, as you slowly
raise the temp., the high heat causes a population explosion of the
parasites - and, some of the fish won't tolerate those high temps
eather... I would treat *half dose* (because of the neons and catfish)
with Rid-Ich or QuickCure. Treat days 1, 4, 7, and 10 with a 20% water
change before each dose. You may have to treat day 13 also because of
the half dose treatments. Oxygen levels will drop with the use of
Formalin - *do not* raise the temp. Malachite Green, at higher temps
and/or lower pH becomes more toxic. It also remains within tissue for a
long time, so you don't want to repeat treatment for a few weeks. It's
important to treat the *full* 10 or 13 days, even if/when you no longer
see any white spots. Malachite Green is also degraded by light, so turn
the tank lights off............... Frank