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Heavy stained (tannins) water, please help

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I recently tried to do a Diana Walstad method tank, so far seems to be doing fine but the water is dark brown, like strong coffee, I used a cheap topsoil from Home Depot called EarthGro, I believe other people have used it ( and capped it off with sea carib eco-complete substrate. so far ammonia 0, nitrites 0 and traces of nitrates
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Water changes are cheaper than regenerating Purigen. Just keep up the water changes because every time you do a water change you are removing tannins. When the problem is that bad (cannot even see the back of the tank) it takes a lot of carbon or purigen to help. I would save these materials for near the end, or when you have gotten rid of 99% of the tannins and want to set up the tank. Then they (either or both) are very good at removing that last little bit of tannins.

Another way to deal with this is before you use the substrate set up a flow through system where the outgoing water might irrigate your garden (to avoid waste). Or at least soak the soil in a container that you can change the water daily (Garbage can, 5 gallon buckets, plastic storage bin...). The more water you pour through the material the faster the tannins go away. You can do this now, sort of like washing the substrate in the tank. Stir it as much as you can before setting things up, and get rid of as much stuff as you can. When you are getting close to setting it up, then go ahead and add rocks and driftwood and sculpt the substrate into whatever hills and valleys you want. From then on, do not disturb it.

Ultimately your aquarium will still have some tannins when you have lost patience and want to get going with the set up. Go for it. The tannins are not harmful. As long as you can see through them to the back of the tank, there is light for the plants. Yes, some of the light is being reduced, but not that much. This is where the purigen or carbon are helpful.

You can add eggshell (well washed), coral sand, oystershell grit or any similar product that will add some minerals slowly, over time. The more acidic the water the faster they will decompose. In more alkaline water they do not decompose. So, the worse the problem (too-acidic water that is too soft) the better they work. I would do anything from a light dusting on the floor of the tank, to an almost solid layer on the floor of the tank. Then mix with the bottom half of the substrate. (I do not like the look of these white materials on the surface of dark substrate). If your tap water is pretty hard (high GH and KH) then you may not really need much else. But if you have soft tap water, then having the additional minerals in the substrate is a good idea. You can add these materials after the set up by placing them in a nylon stocking in the filter. The minerals will dissolve in the water, and the substrate can pick them up.
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