Backyard Aquaponics
A place to discuss aquaponics

I have a bunch of limestone and was thinking of using it to make a waterfall into the tank. What ph would the water be buffered at? I would like to keep it good for nutrient uptake so I may have to scratch the idea.

take about 15ml of water and test the pH.

i would scrape off about 1 gram of flakes and submerge that into the 15ml of water, wait for about 2 hours then test the pH of the water.

then take the difference and that will be the pH change.

if it changes more the .5 then i would not use the limestone.

-DF

take about 15ml of water and test the pH.

i would scrape off about 1 gram of flakes and submerge that into the 15ml of water, wait for about 2 hours then test the pH of the water.

then take the difference and that will be the pH change.

if it changes more the .5 then i would not use the limestone.

-DF

Actually, I would use it if it buffered as high as about 7.6. As the nitrogen cycle gets going well, the pH will want to drop anyway. That will take 6 months or so depending on fish load. I have to add potassium bicarb every day just to keep the pH up. My crushed coral in the system ran out of steam.

Running the test DF describes is a great idea, just to be sure of exactly what you are working with.

Yes run the test to help you decide. I fear though that the limestone may tend to buffer to around 8 which is getting a bit too high for good nutrient uptake. The shells in my system that are buffering to 7.6 are a bit high for my taste at least in this first year of my system.

More good info thanks TCL

Oh and a few notes about tap water and pH measurment. This especially applies if you are on a well.

When you first draw water from the tap, it is likely to have a misleadingly low pH. Mine will test at 7 if I test it right after drawing it from the tap. If I wait till it has time to outgas the CO2, the pH will be around 8. This used to drive me nuts when trying to keep my Hydroponic system pH low. I tested the pH of my tap water which was 7, so why the heck was I needing to add pH down all the time. Reason, the CO2 in the water was acidifying the water right out of the tap and giving a false pH reading of 7. Once the water was cycling in the Hydro system, the CO2 escaped and the limestone from the aquifer makes for hard water.

Just something to keep in mind when trying to sort out pH issues with systems and source water.