It's a gram positive rod, chlorine should kill it. BMC seems to think so although if you are only using the tiny amount found in tap water the BMC can re-establish but you aren't. You should be using more to keep a warm reservoir sterile so that's why I suggested using one or the other. So maybe give one or the other a 2 week trial? Good luck on this whatever you choose to do.A quick search says bti doesnt get killed with chlorene per manufacture. I have a bad gnat issue enough to kill plants but also a bacteria bloom issue as fast as 24hrs. My veg res in basement with cooler temps dont have this issue.
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