Ultrasound

I think I have algae present; it looks green on the surface, beige when I skim it off, and it smells like pond water. The system is near a set of overhead doors, so it gets plenty of outside air and a little bit of sun. We also have fluorescent lighting, which (from what I understand) also promotes algae growth. Are you saying that if I use Baquacil I will need a separate algaecide, or that its algaecidal properties are sufficient for the limited environment I have?

Thanks for the info. I discussed the borate/boric acid option with my boss, and while that combination is used as a corrosion inhibitor in certain applications (nuclear reactor coolant being one), it can also cause corrosion in some circumstances. He pretty much said "no" to that. So I haven't taken any action yet. Based on some of what you've said, and on a whole bunch of surfing around pool sites, I'm seriously considering either Baquacil or a product called "Echocide" which is sold by an ultrasound company (their proprietary blend of N-Alkyl (C12-16)-N,N-dimethyl-Nbenzylammonium chloride). (I see that chloride there, but it's only a small fraction of the total composition of the substance, which will itself be diluted a whole lot.) I have not yet heard from other companies who have tanks like ours, but I've got inquiries out there. Should I even consider either of these two products? Keep in mind that no one will be swimming in this (and I do feel a bit out-of-place posting under this circumstance).

I work for an industrial testing company. We recently purchased a 4000 gallon tank in which we will perform immersion ultrasonic testing. (The principles are similar to medical ultrasound, but we're doing it to metal instead of people.) I now have a pool to take care of, but I have a few unusual conditions. 1. My boss will not allow me to use chlorine (or any other halogens) in any form. Some of our test material is highly sensitive to chlorine in any form; if a customer smells it during a visit, it will cause all kinds of headaches. 2. No one will be swimming in this pool, though people's arms (mostly mine) will be reaching in quite often to adjust equipment. 3. The only things normally going in will be metal pipes and bars. The main contaminants will be dirt, metal oxides, and petroleum-based oils. 4. The tank probably will never be "closed". 5. I don't need to maintain pristine sanitary conditions, just reasonably clean. I'm far more concerned about keeping odors low (my arms smell like algae even now) and keeping mosquitoes and other critters under control (just added a few Mosquito Dunks to kill the wigglers). 6. The tank is lined with stainless steel (304, I think). I don't care if it discolors, as long as it doesn't significantly corrode. Edited to add #7 and #8: 7. We have a Sand Dollar SD40 filter and a 1 Hp pump, though the water doesn't circulate all that vigorously. 8. Air bubbles reflect ultrasound, and that's bad for what we do. I need a solution which doesn't tend to put air bubbles in the water. Ozone systems appear to do that, but I'm not sure. I don't own a pool, so I don't even know where to start. Thanks for any help you can give.