Aqua Soil and pH

Re: Aqua Soil and pH

The drop in KH gradually decreased over two months for me. I used Aquasoil Amazonia over pumice, peat, and mulm in one tank, and Amazoina over mulm in another tank. I found I like soft water though and now pwc with RO/DI mixed with tap to lower KH.

I don't care about my pH anymore after feeling confident about my CO2 injection levels.

Hope this helps.

 

Re: Aqua Soil and pH

It is never an accurate way to measure CO2, but it will be as accurate as it always is. The key is that nothing in the water changes when it degasses except the amount of CO2 dissolved in it. The problem is that we never can be sure just how far outgassed it is, and the pH change depends on how far it outgasses.

 

Re: Aqua Soil and pH

I agree, but it would be much more accurate than the ph/KH tables, since it would not require assumptions about sources of alkalinity or acidity. My only reservation about trying to use this method is evaporation of the samples as they sit there outgassing. Evaporation raises the KH. That kills the equation that relates pH drop to ppm of CO2. But, I don't have my head working well enough to see if the evaporation of both the reference sample and the tank sample, assuming both are in the same size and shape vessel, raising both of their KH's would compensate. Maybe when my brain is ready to shift into high gear again I will try to figure that out - but I hope someone with a finely tuned brain will beat me to it.

 

Re: Aqua Soil and pH

Could top off with more RO/DI if its very important to you. In the end such a skewing of the data is probably less than the %error of the test, so you can ignore it. Better guess is the most realistic goal with any hobby grade kit.

However, if you reconsitute KH of DI with known (weighted) bicarb, dependency on the KH test is gone and then its just the (in)accuracy of the pH test you care about. (Thinking realistically.)

 

Re: Aqua Soil and pH

In my condo 48 hours sitting on the kitchen counter in a wide mouth container would result in evaporation of about half of the water, and that would double the KH. You can add more DI/RO water to make up the difference, but that water would have to have been degassing alongside the other samples. Now, how do you make up the water loss in the tank sample? Would adding DI/RO water from an outgassed supply do it? Yes, tentatively, it looks like it would.

I threw up my hands when contemplating how long such a test would take, and all of the new errors that might be introduced. My last try was blowing into a sample of RO water to see if a repeatable amount of CO2 could be introduced without causing me to faint first. That's when I gave up totally on measuring CO2.

 

Re: Aqua Soil and pH

I agree. This method looks promising, and once you find that, in your kitchen, using your brandy sniffer, after 48 hours a water sample has, say, 0.7 ppm of CO2 in it, all you need to do after that is just let the tank sample sit for 48 hours in the same size brandy sniffer, measure its pH and compare it to the in-tank water. Then use the equation CO2 ppm=(Degassed CO2 ppm)X10exp(degassed pH - in tank pH) to calculate the CO2 ppm in the tank.

 

Re: Aqua Soil and pH

I stuck the method in the planted tank forum to try to get several people to try it and report what they found. I may try it myself today if I feel up to it. But, my pH meter may have dried out by now from lack of use. I seriously doubt that I will ever do this method twice - I like my own "watch the fish and algae" method much better. (Even if it does treat the fish a bit badly.)