my aquarium pH down by API is sulfuric acid. it contains no phosphates. the product specs say that it can be used on live plants. check out the manufacturers website and read the MSDS or product specifications. sounds like it will work.

on the other hand you can get something made specifically for plants. general hydroponics pH down uses food grade phosphoric acid.

ditch the probe meter. get a pH test pen. they can be found on ebay for ~$25.


-shake