Pond Boss Forums INTRO Questions & Observations Low Alkalinity

HI I checked my ph and it is at around 6.2 but my alkalinity is below 20, last year I added 2.5 gallons of Cal Flo liquid lime that bought my ph high at the time to 9 and alk. around 60 but now its like it didnt last, do I need to try a different process. the pond is a half acre around 8 ft. deep

What is your main goal to be reached by altering your alkalinity? Hard to evaluate the bang for the buck without knowing the ultimate goal.

Typically you want the alkalinity over 40 ppm so plants and phytoplankton can utilize the nutrients in the water. Low alkalinity is like having very low pH in soil. It locks up the nutrients, making them inaccessible to plants.

That's why it's not recommended to fertilize water to get a bloom until you can get the alkalinity up. There might already be plenty of fertilizer in the water already.

Ervin: Look into getting agriculture lime (dry) and spreading it out in the pond.

One of these methods

ag lime


or bag lime (not hydrated)

If using the ag lime in the bags how many do think I need to start with

Start out with applying 2,000 pounds. although I'd really like to see you use regular ag lime due to the binder that is used to make the pelletized lime.

See: https://www.aces.edu/blog/topics/fish-water/adding-agricultural-lime-to-fishponds/

Regular ag lime is better but if you can't get it then use bag lime. Start with a ton of ag lime. More won't hurt and will help. Test 2 weeks after application and see where you are.

Is there a source for dolomite stone or similar available to you? lining the pond and inlet with a variety of sizes up to riprap may be a long term option as dolomite contains mostly magnesium carbonate and some calcium carbonate which will buffer the PH to some degree.
Not as efficient as ag lime, but may be able to sustain the buffer after initial treatment.