Agree with the plant dip for a variety of reasons (snail and parasites), but you'll find BBA spores in the air, so you can't totally keep it out that way. BBA is caused by fluctuating CO2, varying nutrients and/or too much light. Most of the time, it's too much light that is the culprit (in non-co2-enriched tanks, anyway). It's a pain to get rid of but my first recommendation to battle BBA is to reduce the light intensity and photoperiod (below 8 hours/day, might go as low as 6/day temporarily). there are LOTs of anti-BBA threads here, but prune as much out as you can, clean any hardscape to remove BBA that's taken up residence, and you can try "Excel" to inhibit the algae growth a bit (caution, a few plants don't like Excel at all).
I don't want to further hijack this thread, so if you want more on exactly what I've done, shoot me a PM, but what I said above is basically it.
Main issue I see is a T5HO light on a 20" deep tank = too much light intensity! Try using fiberglass window screening over the tank to cut the light by 40%
Last edited by DKRST; 12-30-2013 at 01:57 PM..