We have a good deal of bacteria that like to reproduce in our gold plating rinses. We have had them for years and they have not caused a defect yet. We have done some lab studies and consulted with some microbiologist at the University of Texas to see what we could do to get rid of them. There are a number of algaecides and antibiotics that will work but the "bugs" will become resistant over time. You have to rotate through a treatment reigme to keep their populations in check. They don't seem to favor the gold baths. We surmise that the temp and/or cyanide concentration is too high. The algaecides/antibiotics that we considered were to be used in such low concentrations that we were not concerned with pass-through We simply use household bleach at 5% v/v on a maintenance schedules. Since the bleach attacks their cell walls, they can not become resistant. Michael Holan Radian International, LLC Elecronics Div. 512/310-4209 [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Algaecides/Biocides Author: [log in to unmask] at INTERNET Date: 6/5/96 7:03 PM Hi everybody! I am looking for some information about reducing algae and bacterial growth in process baths. In the last few weeks, I've had several engineers propose some rather nasty chemicals they wanted to add to either gold baths, or photodeveloping baths to stop algae from growing. Does anyone else have this problem? What do you use? Do you have any concerns about pass-through to your POTW? I talked to some guys from DuPont at IPC Expo, and they weren't too concerned about pass-through. However, they were selling photochemistry also!! (Sorry about that, John Lott. I had to get that in.) I would appreciate any information, abuse, snide comments, etc. John Sharp Merix Corporation Forest Grove, OR Operations 503-359-9300 (ext. 5-4351) 503-359-1040 FAX [log in to unmask]