I'm starting this new thread in hopes of getting some "bites" from the experts. Dealing with 3 small tanks sick with velvet. 2 of them are 2.5 gal betta tanks housing betta and couple of ghost shrimp, and 20 gal community with betta, 1 adult Molly and platy and 2 baby mollies and 1 baby platy (believe all are female except for betta boy), 2 mystery snails and couple of ghost shrimp. All 3 tanks filtered and heated, all heavily planted with live plants. On day #3 of Mardel Quick Cure today. All 2 tanks ammonia readings at zero as are the nitrites and ... surprisingly nitrates at zero as well!!! Is that something that has to do with the medicine or the filter carbon being out? Bcs couple of days ago I'd still get good nitrate readings on all 3 tanks. Couple of SOLID QUESTIONS here: 1) my bettas and one of the community fish still show that "gold dust" when I flash the light on them. They eat great and one that looked the sickest (hanging out at the water surface all the time) is back to patrolling his home as he's always done, the Mardel box says to treat for 3 days. What has your experience been? Stop or continue since there is still the o"gold dust"? 2) how soon after the treatment do I replace the filter cartridges and what's best way to do it as to not lose too much of the bb that have probably been already compromised by using Mardel? 3) I removed the snails from the sick tanks but good luck with catching those ghost shrimp in planted as heck little tank... So sorry to admit but I decided to sacrifice them in order to save my fish... Well... I'm seeing some of those boogers still there!!! Hate to have put all that stress on them... But few were just eating dinner just now! The onset of velvet coincided with introduction of the snails to the tank (then I used same syringe to pull water for testing out of each tank.... Yes! I know! Bang!!!!!) my lfs people say that it is unlikely for the invertebrates to cause illness in fish.... But to think about it... About this same time I brought home baby platy who has died (my second casualty since Feb'13) .... So maybe it was the platy who started this??? Who knows? Anyway, do you guys think I should try to reintroduce the snails back in the tank? And when? Moved them into temporary planted bowl for now, have to change water (partial) to keep ammonia down.