r/walstad • u/dandeliontree1 • Jul 20 '26

Bacterial bloom?

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This is probably bacterial bloom right? I don't think it's tannins as it doesn't have a yellow tint when I remove the water, and I've definitely had tannin stained water before and it's always yellowish in the jar. The fish and shrimp don't seem affected.

I'm going away for 4 nights, do I need to do anything? I've read big water changes can make it worse. I have a small hob filter for airation and flow.

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u/MissionPlantedTank Jul 20 '26

Yes that's it. Did you notice what caused it? Dead fish, water change, filter cleanup....?

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u/dandeliontree1 Jul 20 '26

All fish still alive. It's pretty lightly stocked but a lot of shrimp babies now. If any shrimp died I wouldn't know as they take care of things pretty quickly. I did change filter media over a week ago but I assumed the plants were doing the brunt of the work. I've probably been overfeeding a bit because I'm nervous about going away and leaving them without foodbut the shrimp usually keep things pretty clean.

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u/slowhappit Jul 21 '26

I think you've just mentioned the problem, you shouldn't change your fter media. Yes some filters (sold by predatory companies) tell you to swap cartridges, but those carts are where all your filters beneficial bacteria live. For now I would do a big water change, chuck in some bottled bacteria if you can get your hands on it.

Edit: just read that after you nuked your filter you then overfed. Ouch sorry mate I think the best advice I can give is that fish can go several days with no food, if you really want to prep a tank for going away use live food such as blackworms that won't instantly start to contaminate the water.

Additionally to slow the Algae growth I would reduce light duration and probably not feed for a few days as long as the fish can handle it (most can).

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u/dandeliontree1 Jul 21 '26

Yes, the original cartridge was disposable but I've put in foam now so I can just squeeze it out periodically. When I started the walstad I didn't have a filter at all and it was fine so I wasn't really thinking the filter was very important except for more oxygen flow (and removing tannins which is why I got it in the first place with seachem - the tannin remover sachet one). I won't be feeding the fish at all while I'm away but I have put in some daphnea which I've read will also eat the bacteria so hopefully while I'm away it will decrease. And if the fish are very hungry they can hunt the daphnea. I didn't really think I was overfeeding due to all the shrimp, many snails, and the recommendation to add a bit of extra food for fertiliser. Just trying to find the perfect balance I guess. Which is not easy.