Day 36

[yuki71]

ok
ph now at 6.6
nitrites off the chart(purple straight away)
nitrates at 20ppm and been that way for some time
dosing amonia at 3 clears very quickly and been that way for some time
40x16x16 sand base with tetratec ex1200
nothing seems to be moving

any thoughts very welcome

 

[locust267]

Could be low ph, try dissolving some bicarb in tank water before adding to tank (I wouldn't do this once in tank but it will help growth of bacteria). For longer term results if you wanted higher ph put crushed coral in a stocking in your filter.

A large water change may also speed things up.

 

[HayzH]

this is classic ... you Nitrites are high...so the crash your pH..This Stalls the cycle. your bacteria love PH 8.0 to breed ... add Bicarb (teaspoon at a time) leave for an hour then test ph again) till you get it to 8.0.
Sounds like you live in a soft water area too