Originally Posted by MarkW19
I'm disappointed that the nitrites wouldn't be the problem, I thought I'd cracked it. Those levels of nitrites shouldn't be in my PWC
water though, should they?
Correct... you shouldn't be seeing ANY nitrites in the water, so something is wrong. While I'm no marine biologist, I don't think those levels of nitrites though are enough to be the instant killer that you've seen.
HOWEVER... with the test showing nitrites, I would start to suspect some kind of contamination of your water that could just be showing up on the nitrite test - but isn't actually nitrites.
I'm with you - I doubt it's your salt. It's not like Seachem is some no-name brand, and the fact that you've been using it for 6 years with no problems seems to point elsewhere.
Along the lines of what you said about the buckets, if it was me, I'd go buy new buckets and a new powerhead (or at least a different one) and start "fresh" with new equipment to rule out that possibility.
... When I said "test strip", I meant the results strip where you compare the colour of the water, with the strip.