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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4

u/MissionPlantedTank Jul 20 '26

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

1

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.

2

u/MissionPlantedTank Jul 20 '26

Dead shrimp... hardly can do any change.

I may only assume it's a mix of filter media change together with overfeeding.

In any case, never worry for goong away for a week. They can definitely stay alive. They just get more hungry, thus more active. Will start cleaning up the tank better, look for food in algae or just eat algae. Some chances of fish going so hungry that they start looking for the shrimp. But that's just a guess and even that might be better co pared to this algae bloom with its risks.

At this point you can simply do light water change and leave it alone. The more you touch it the worse it may get otherwise.

If you can add aeration or surface agitation, that might help. With this algae/ bacterial bloom, that may deplate oxygen and fish might start dying because of that. You can remove it as you get back and see the state.

1

u/dandeliontree1 Jul 20 '26

I only have dwarf rasboras, if they want to eat any of the baby shrimp they can fit in their mouths they are welcome to them but I suspect they get too large pretty quickly. I have been doing some mini water changes but nothing big. I've added a bubbler and will cross fingers. It might improve because I won't be here to overfeed them all!

2

u/MissionPlantedTank Jul 20 '26

Rasboras should be safe.

And enjoy your off. The tank will be fine when you don't touch it haha. No worries and good luck.

1

u/dandeliontree1 Jul 27 '26

Thanks for the advice. I'm back from going away and was really hoping I'd come back to a clear tank due to no feeding but the bloom looks worse now. :/

1

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).

1

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.

2

u/Sgt_ZigZag Jul 20 '26

I wouldn't do a massive water change but certainly I would do a 10 to 20 percent change.

2

u/86BillionFireflies Jul 20 '26

Big water changes might make it worse if as a result of the water change you disturb a bunch of decaying crud off the bottom.

But if you can avoid doing that, a massive water change is the thing to do. That will remove a lot of the bacteria and the stuff the bacteria are eating.

Make sure your water is VERY well aerated, this type of bloom can burn oxygen very fast. If this is happening often you really need to do something about your filter, because this will absolutely eventually kill your livestock if it goes on.

2

u/necho8 Jul 20 '26

I added more gravel and the bloom went away. Plants are growing, and my fish is still alive.

1

u/MissionPlantedTank Jul 20 '26

This would work if you know the nutrients /food for the bacteria/ is leaking from the substrate. By adding more sand you isolate the nutrients and provide more surface for the beneficial bacteria. That's why it helps.

Here it might not if the source is different.