micro bubbles in your dt from your return pump is always caused by air being pulled into the return pump in your sump,what is the depth of water in the return pump section,how is the water flowing into the return pump section?,a few photo's of your sump setup would help.
As for the chaeto and algae,whats your water test results
Chaeto wont grow within 2 days,where is the chaeto(good flow) is it floating or has it sunk?
Chaeto tends to grow when its in good flow and is tumbling(but needs nutrients hence test results),if not then just good flow and under light,light schedule opposite dt lighting is fine.
Old Chinese proverb:
Don't go to bed with ichy bum
wake up with smelly finger!!