Like others I've used The Geo Method for tank treatment and never have had any tank odour issues regardless of summertime temperatures. Last year a friend mentioned success he'd had with Walex grey and black tank treatments so I've been using it since, again with great success. Since I always service my tanks at home using my FloJet Waste Macerator I can take whatever time I want with this process so I do continue to Geo the tanks during that process, then once cleaned add Walex to the tanks ... no issues with tank odour at all. :B
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