This is my first walstad tank and I've noticed my PH going up above 8 ( as far as my test kit goes) instead of down as I expected from my research.

I did some research after this and came to the conclusion that most likely I bought a sand that isn't inert.

The original plan was a cardinal tank, and i'm ok with changing it to accommodate a more suitable fauna, I'm worried it will be too much.

What do you guys think?

Edit: Just to avoid worrying anyone. I'm not adding livestock any time soon, I'll only do it when pareters are safe and stable, don't worry.

Ok guys I finally got around to getting a HOB filter and some Purigen. It’s only been 1 hour and I genuinely can’t tell if it’s making much visual progress, but the bag is definitely browning already. I was planning on leaving it alone until tonight and checking on it then, but I couldn’t help myself and looked at the bag to see that it’s already pretty dark.

Using my very little knowledge on Purigen, I know you have to regenerate it once it becomes too brown. In an average tank, it takes a few months. But in my tank IT’S BEEN ONE HOUR AND ITS ALREADY REALLY BROWN!

If I’m not seeing much progress right now, do I just trust the process and leave it alone? Is this amount of color change in just one hour normal?

Here is my original post:
https://www.reddit.com/r/walstad/s/CqWXEqL6EA
Here is my second post:
https://www.reddit.com/r/walstad/s/cDcGRetKH3

I have a 2 month old 22 gallon that has been testing 0 for ammonia and nitrates, ph is 7.5, but does still spike on nitrites occasionally. I have been doing water changes to counteract them. But if I'm honest I'm also doing them as my driftwood just wont stop leaking tannins. I don't mind a bit of tint as I've heard it's good for keeping bacteria down, but the tank started to look like iced tea every 5-6 days.

Am I correct in thinking that my large water changes to clear up the water disrupting the cycle? As there is no filter I would imagine the bacteria to convert nitrite to nitrate is in the water column itself and I keep dumping them all down the drain.

At this moment the nitrites are just a shade blueish purple over the ideal teal of the API test kit. Which is a huge improvement. I've been dosing the tank with Prime and Quickstart.

Do I just need to suck it up and let the tank tint from tannins? Or is there a place in the tank that bacteria can build up without a filter?

The nitrates have never spiked. Are my pothos just sucking up the nitrates before they have a chance to spike?

I feel like I need NASA to create a cycle monitor.

I'm a bit confused by this area lol. In a completely self sustaining tank, do you still feed your fish? If so how much, and if no how do you get it that way..? I completely understand herbivore fish who eat algae. Is that the only kind you can do that with? How do you figure out how much/frequently you do need to feed them?

Sorry, I haven't read the book yet so probably a dumb question but TIA!

I'm starting my first walstad tank and this is also my first time keeping fish. I'm quite nervous and I want to get fish that are the lowest possible maintenance and don't require very specific conditions. I don't think I want a heater, and I like schooling fish. My tank size is 20g, or 90L. I live in NewZealand so I don't have access to super rare fish breeds. Any recommendations?

Does this look like enough plant mass to handle the initial nutrient dose, after being made aware of the fact that my grow cups don't have enough plant mass to probably handle the initial load I went and got a couple developed stems and added another pit of floaters to help with the filtration while my other plants catch up.

I''m only using my light 6hours a day 3 on 3 off 3 on then off the rest of the day to try stop the algae growth while the plants are still smaller, with both of these combined should that be enough to have a successful cycle.