have you tested the tap for nitrate? 80ppm should not be causing problems, however you should not see levels like that in a properly cared for tank. Nitrate is not something to concern yourself about too much. Ammonia and nitrite are the most important tests.
Yeh I tested the tap water. I thought the tap water was high for nitrate, turning the test a pale red, around 80ppm (API Liquid Nitrate test).
Looks as though I'll need to get myself the ammonia and nitrite test
I (stupidly) presumed if there was trace of nitrate then the filter/bacteria was doing its job at converting the ammonia and nitrite. Hope I'm not too late to get the test kits and solve this! I hardly ever test the water only when something goes bad (like now!

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