I agree, 14 day copper treatments, especially with Cupramine, and if the infection rate is low, CAN work against ich. As I’ve said though, it really should be 14 days beyond the day the last trophont was seen. My tolerance is much lower,I guess you can blame a lot of this on me. I was the one who pushed the idea of shorter copper treatments with a transfer. I bombarded Bobby with literature convincing him it would work, and based on the scientific literature I had available, it made a great deal of sense and it seemed to be very effective.
I would still say that this is effective the majority of the time. As I see it, the flaw in my logic was assuming that a trophont will leave it's host within 7 days and then adding some margin. I have come to suspect that the copper treatment itself will slow trophont development and cause it to remain on the fish longer. The type of copper used, temperature of the system, and O2 levels in the system are also likely to play a role.
So, while the 14 day treatment with transfer is probably "good enough" for most strains of crypto and conditions the fish are kept in, it isn't going to be perfect. Jay is basing his recommendations on systems that have a much lower tolerance for risk than most hobbyists.
As for coppers impact on tomonts, I cannot find any studies that were done on the long term exposure of tomonts to copper treated water. I have seen it theorized that exposure to copper treated water for longer periods of time causes the resulting tomites to not be viable to reproduce. Unfortunately, I haven't seen any studies where this has been tested.
The only other research I've seen shows that tomonts which are formed on copper sheets or copper alloys will be killed by that copper. This may explain why ionic copper is more effective at shorter treatment times than chelated copper products. While that is speculative, it does show that tomonts can be impacted by copper.
Don’t forget - that copper sheet study was done with 2x daily water changes apparently done to reduce the toxicity to the fish. It is really tough to sus that out from the paper, almost like they were trying to hide that aspect.
Jay
