ADA Aquasoil - effects on water chemistry? - The Planted Tank Forum
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post #1 of 7 (permalink) Old 06-25-2014, 04:39 PM Thread Starter
Algae Grower
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ADA Aquasoil - effects on water chemistry?

I bought two 9 liter bags of ADA Aquasoil Amazonia for my 46g planted tank. It states that the soil lowers ph, and softens water making it suitable for most plants, and is clay based which is great for most root feeders.

Background. I've had this tank up and running for several months now, light - medium stocked with plants, heavily stocked with fish. Nitrates reach 20ppm inside a week, so I've been doing two water changes per week lately. I have also started dosing dry ferts - K2SO4, KH2PO4, and CSM+B. 1/8teaspoon of each, three times a week.

I have been testing the water parameters on this tank quite bit lately. I just started up CO2 injection and I wanted to see what my ph was sitting at. So... here we go. Ph out of tap is 8.2, after sitting for 24 hours, its 7.2. Ph in the 46g with the aquasoil is 6.4. I have been testing this since day one, and it has not changed. The ph is always at 6.4 and there has been no fluctuation.

Dig a little deeper. Kh out of tap is 4, and Gh is 9. Kh in the 46g.... undetectable, Gh in the 46g is 6. TDS of tap 177ppm, TDS in tank 193ppm.

So not sure what the deal is with the KH, but I tested several times. The first drop in the tube and the water turns yellow.
Is this even possible or is something in the substrate leeching out and throwing off this test?
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post #2 of 7 (permalink) Old 06-25-2014, 05:42 PM
Algae Grower
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Soil is absorbing hardness and buffering pH, and feeding the fish increases TDS.
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post #3 of 7 (permalink) Old 06-25-2014, 07:40 PM Thread Starter
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My guess is the soil is absorbing Ca, and Mg, but by doing so it's definitely not buffering the ph, it's removing the buffer...

What I don't understand is how it can absorb, or adsorb the bicarbonate... I was pretty shocked to see the KH so low, or undetecable.

Feeding the fish maybe increases TDS, but not in measureable amounts - the increase in TDS is probably from dry dosing...
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post #4 of 7 (permalink) Old 06-29-2014, 08:57 AM
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It's a chemical adsorbation. For sure it's the aquasoil taking in the co3 and mg/ca. TDS is in ppm = mg/L. So yes, dry dosing will raise the TDS, fish food will, water evaporation, and even the soil can leech TDS if it breaks down
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post #5 of 7 (permalink) Old 06-29-2014, 11:11 AM
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A substrate that lowers the pH does so by removing the carbonates in the water, which allows the pH to drop. So if you have a kh or 4 in your tap water and you add that to a tank with aquasoil it will absorb the kh and as a result your ph will drop. There is nothing wrong with your test kit, the soil is doing what it is designed to do.

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post #6 of 7 (permalink) Old 06-29-2014, 08:52 PM
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Ammonia: increase (only first few weeks)
pH: decrease
hardness (KH): decrease
tannins: increase (limited)


My Golden Rule of planted tanks: WWTAD-
"What would Takashi Amano do?"

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post #7 of 7 (permalink) Old 06-30-2014, 09:34 PM Thread Starter
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Thanks guys. Guess I was just shocked to see KH so low. Is the substrate peat based or something?
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