Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
'Scrubber' is a general term for any plant (including algae) that removes nitrogen. In this case the algae scrubber is removing the nitrogen (ammonia, nitrite or nitrate), keeping it low between water changes.
I would swap fish. Put the Gold in the big tank, no other fish.
Put the Guppies in the small tank, and even then you could double the population, as long as you stick with males only.
If they want to raise the population faster then do this:
1) UV sterilizer to kill algae. Do a pretty big water change, or a couple of them to remove the dead (decomposing) algae while the UV is doing its job.
2) When the algae seems gone continue to monitor the ammonia, nitrite, nitrate for a few days. Do water changes as needed.
3) A few days after the UV has been removed, the algae is dead, and the ammonia, nitrite and nitrate have settled down, add some bacteria from a bottle that contains Nitrospira species of bacteria. Do not waste money on anything else. Read the instructions, and do not do any water changes for a few days. Let the new bacteria get a good hold on the filter media. Make sure the person who does the regular water changes understands not to do them for a few days. (Or, if you know what day he comes in, do this the next day, knowing he won't be back for a week)
4) Add fish within 24 hours.