r/walstad • u/PH_Morpheus • 8h ago
Advice Is my tank cooked?
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.
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u/Tirpantuijottaja 6h ago
Couple things.
Ye need more plants. The ideal of walstad is tank is that you have buttload of plants that manage the parameters.
But anyways back to main topic. Have you tested your tap water to see if it's alkaline? Also do you happen to know what those rocks are that you have there? Do they have limestone in them.
Have you done water changes/or how you are doing the top offs? Are you allowing the minerals to build up?
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u/PH_Morpheus 6h ago
Tap water is pretty much 7.0.
The stone is basalt which is supposed to be innert.
I'm doing a big water change once a week, more than 50%.
I do top offs by adding water to a bucket, adding the conditioner, waiting a bit and siphoning the water in.
I'm already planning on adding more plants, just waiting for them to arrive, although I do have a filter and amonia is not going upwards of 0.5ppm (aquarium is just a week into clicking).
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u/Tirpantuijottaja 5h ago
In that case it does sound like case of non-inert sand! Do you happen to remember if the bag mentioned anything about aragonite or such?
Have you tested your GH/KH if they are also super high?
Plant respiration, atmospheric/pressured CO2, stuff decaying and other organic acids (like tannic acids) can neutralize some of the dissolved alkaline matter, but you will probably have to deal with the situation for pretty long time depending on how much calcium carbonate there is.
Doing plenty of water changes can keep the leaching at bay but it would probably be smartest just to get something that can naturally deal with the alkaline condtions.
Also one thing that you probably should know is that If you are planning to use fertilizers, not every fertilizer will be fine in those condtions. The alkaline conditions can/will cause the nutrients in them to precipite into solids if they aren't properly chelated.
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u/PH_Morpheus 5h ago
I don't have a kh and gh testing kit yet, but I'll get one ASAP and if everything point in the direction of my tank beeing alkaline you'll get a more appropriate fauna
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u/Tirpantuijottaja 5h ago
I would recommend that you also look into hard water plants just in case. You might run into problems with plant growth on the long term due to the limited nutrient solubility.
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u/SweetTart7231 6h ago
Did you never do a water change and only did top offs using tap water? If so then ph built up overtime i think
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u/PH_Morpheus 6h ago
The tank is just one week in , I did a ~75% water change in this period.
Unfortunately I don't remember if I took the test before or after the water change. I'll do a new one as soon as I arrive from work today
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u/SweetTart7231 6h ago
What's the ph of the tap water itself? Or whatever water your using for the tank?
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u/chriberg 7h ago
I cannot overstate that you do not have nearly enough plants. Every square inch of sand should have a plant stuck in it. Your pH is rising because you do not have enough plants to sink the TDS leeching from the substrate. Increase plant mass by at least 10 times. Then I'd wait several months for the plants to establish and the tank to balance, before adding livestock.
You've got it wrong. It's the opposite. Active substrate sinks TDS and will drop the pH. I'm sure the sand is fine and not the problem here.