It's entirely possible that the ratio of nutrients in the fish mix is such that all of some necessary nutrient for the chlorella is used up before all of the ammonia is purged that's why I'm keen to be able to test mine but it wouldn't necessarily explain why me and miranda don't seem to be having the same issue. It would be another huge point in favour of dry salts though. Lacking any dry salts I'm going to try a bottle with tropica specialised fertiliser and see how that goes.
The main reason I initially went with fishmix was that I'd used it before and it had the sugar in it. The guy from the parosphromenus project who really seemed to know what he was talking about when it came to chlorella and moina, and was speaking from experience, was also adamant that a 6-1 N-P ratio was ideal. Fishmix is 5-1 and was the closest I could find at the time.
Another thing to consider is that being an organic product the fish mix is likely to vary slightly from bottle to bottle.
I'm not at all married to the idea of using fishmix, I'd be really happy to find something that works better.
Yeah, I had wondered if the existing ammonia was linked to another nutrient running out, so I have added some micros and macros to the fish mix based cultures that I have decanted into bottles in the hope of using it up.
The main culture I have running now based on just dry salts seems to be running well, and I’m definitely seeing a decent growth in Chlorella. It’s hard to tell if it is as fast as the fish mix one, because the water in the dry salts version is clear, so it automatically looks less dense than the brown coloured fish mix version.
It’s is also difficult to know how much ferts should be added. I will periodically use a nitrate or phosphate test kit to test the mixture - I know these kits are inherently inaccurate, but all I’m looking for is a non-zero colouration value versus a zero colouration value, so they should be accurate for that rough test.
My main Moina culture has crashed completely now with no survivors, despite the water changes. However it is measuring zero ammonia and nitrite now, so I assume the sponge filter is cycled and doing its job.
The water it still heavily clouded though. I have no idea if that is Chlorella or bacteria or something else. As @MirandaB suggests, I have added loads of floating plants to the culture too. It’s the first time I’ve actually managed to get my red root floaters to turn bright red under the super high light of the AI Prime.
I wil carry on with the water changes on this tank with the aim of it being bacterially stable eventually. Then in a few weeks I’ll rematch some more Moina and add them.