OK, did a big water change, ( about 95% )double dosed dechlorinator and dosed ammonia back up to 2ppm. Waited for an hour after changing water and dosing to measure parameters. Ammonia = 2ppm, nitrite = 0, nitrate = 5ppm, but worryingly ph = 8.
If my ph goes up to 8 after a water change, won't...