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Hi, I've recently set up a low-tech/Walstad style tank with a soil base under a sand cap. The plants are thriving, but I've had a couple of 'explosions' from under the sand over the past two weeks - absolute chaos. Luckily, there aren't any fish in the tank yet.

A few questions, really...

* Has anyone had to lift all their plants, change the substrate, and replant? How did the plants handle it?
* Will I have to deal with these explosions on an ongoing basis, or will things settle down once the tank's established?
* How effective is using sand with fertilizer tabs for the plants - is it a viable alternative?

Any advice would be greatly appreciated, thanks.

I'm not sure if you'll experience these 'explosions' again, but I did have a similar issue with my clown loaches digging up the soil in my tank. Although it's not a Walstad tank, I imagine the process of replanting and cleaning would be similar.

I removed all my plants, cleaned off the remaining soil and mud, and pruned any dead or damaged leaves and roots. It was a necessity, given the state of the tank at the time. If you don't have to do a thorough cleaning, I wouldn't recommend it. I used tap water, making sure the temperature was close to the tank's temperature.

After replanting in sand with fertiliser tablets, none of my plants died. In fact, some of my tiger lilies are growing faster now than they were before. Now, when I clean the tank, I use a skewer to quickly release any air bubbles trapped in the sand.

It would be helpful to know what plants you have in your tank. I have relatively low-maintenance plants, but I'm aware some plants can be more finicky.

daisymay wrote: ↑Sat Jun 24, 2023 6:01 pm Hi, I've recently set up a low-tech/Walstad style tank with a soil base under a sand cap. The plants are thriving, but I've had a couple of 'explosions' from under the sand over the past two weeks - absolute chaos. Luckily, there aren't any fish in the tank yet.

A few questions, really...

* Has anyone had to lift all their plants, change the substrate, and replant? How did the plants handle it?
* Will I have to deal with these explosions on an ongoing basis, or will things settle down once the tank's established?
* How effective is using sand with fertilizer tabs for the plants - is it a viable alternative?

Any advice would be greatly appreciated, thanks.

I've had a similar experience. My plants bounced back just fine. The crypts and vals did go through a bit of a meltdown initially, but they've come out stronger on the other side.

Regarding fertiliser tabs in sand, I've found it to be a very effective method. Not only is it more budget-friendly, but it's also more nutrient-efficient in the long run.

kingrise wrote: ↑Sat Jun 24, 2023 8:19 pm

daisymay wrote: ↑Sat Jun 24, 2023 6:01 pm Hi, I've recently set up a low-tech/Walstad style tank with a soil base under a sand cap. The plants are thriving, but I've had a couple of 'explosions' from under the sand over the past two weeks - absolute chaos. Luckily, there aren't any fish in the tank yet.

A few questions, really...

* Has anyone had to lift all their plants, change the substrate, and replant? How did the plants handle it?
* Will I have to deal with these explosions on an ongoing basis, or will things settle down once the tank's established?
* How effective is using sand with fertilizer tabs for the plants - is it a viable alternative?

Any advice would be greatly appreciated, thanks.

I've had a similar experience. My plants bounced back just fine. The crypts and vals did go through a bit of a meltdown initially, but they've come out stronger on the other side.

Regarding fertiliser tabs in sand, I've found it to be a very effective method. Not only is it more budget-friendly, but it's also more nutrient-efficient in the long run.

It seems like there are pockets of air or gas accumulating in the substrate, and when they're disturbed, they suddenly release, sending the lower layer of soil flying everywhere and covering the sand cap.

kingrise wrote: ↑Sat Jun 24, 2023 8:19 pm

daisymay wrote: ↑Sat Jun 24, 2023 6:01 pm Hi, I've recently set up a low-tech/Walstad style tank with a soil base under a sand cap. The plants are thriving, but I've had a couple of 'explosions' from under the sand over the past two weeks - absolute chaos. Luckily, there aren't any fish in the tank yet.

A few questions, really...

* Has anyone had to lift all their plants, change the substrate, and replant? How did the plants handle it?
* Will I have to deal with these explosions on an ongoing basis, or will things settle down once the tank's established?
* How effective is using sand with fertilizer tabs for the plants - is it a viable alternative?

Any advice would be greatly appreciated, thanks.

I've had a similar experience. My plants bounced back just fine. The crypts and vals did go through a bit of a meltdown initially, but they've come out stronger on the other side.

Regarding fertiliser tabs in sand, I've found it to be a very effective method. Not only is it more budget-friendly, but it's also more nutrient-efficient in the long run.

I was poking the substrate due to a visible bulge, which I'm convinced would've caused the explosion anyway, likely sooner rather than later. My plants are mostly 'easy care' types, except for a Monte Carlo, listed as medium. I'll post a proper list and photo later, after I'm done with work.

daisymay wrote: ↑Sat Jun 24, 2023 6:01 pm Hi, I've recently set up a low-tech/Walstad style tank with a soil base under a sand cap. The plants are thriving, but I've had a couple of 'explosions' from under the sand over the past two weeks - absolute chaos. Luckily, there aren't any fish in the tank yet.

A few questions, really...

* Has anyone had to lift all their plants, change the substrate, and replant? How did the plants handle it?
* Will I have to deal with these explosions on an ongoing basis, or will things settle down once the tank's established?
* How effective is using sand with fertilizer tabs for the plants - is it a viable alternative?

Any advice would be greatly appreciated, thanks.

I'm really curious, can you show us what these air pockets look like?

The gas being released is probably not the usual nitrogen and oxygen mix, but rather something more like methane - and if you're unlucky, hydrogen sulfide too. This suggests a lot of organic matter breaking down in the substrate. It's similar to what happens when you disturb the bottom of a swampy lake area and bubbles start rising up everywhere. If I were in your shoes and dealing with a lot of gas production, I'd definitely consider re-working the substrate. If I were to set up my tanks again, I think I'd opt for sand, like kingrise mentioned.

I think I've got to the bottom of this – it makes sense based on my other reading too. The smell wasn't exactly pleasant, and this is the state it's left my tank in. I'm pretty sure I'll be doing a full strip-out over the weekend. On the surface, I just don't like the look of all this mud, but more importantly, I'm worried it could be toxic to my fish once I introduce them.

I've been suspecting this might be the case, and it makes sense with what I've read elsewhere. The smell wasn't exactly pleasant either. As you can see from the photos, it's made a right mess of my tank.

I'm thinking of stripping it out completely over the weekend. Aesthetically, I'm not a fan of the mud everywhere, but more importantly, it's a potential threat to the fish once I introduce them. If it's indeed hydrogen sulfide, that's a major concern.

Definitely not good. I'd tear down the tank and redo it, no question. You'll keep having those air pockets pop, releasing excess ammonia and gases that can be really bad for your fish.