Test your KH (buffering capacity).Thx for input! And yeah esp. if you've got a decent sized tank you can go through those 150ml bottles pretty quick, so not super cheap esp. longer run.
By the way, with the Indian Almond leaves do you worry about PH fluctuations or are they negligible?
I recently have got some 'Wish Arowana Spa' (by Medifish) but haven't tried it yet. Ingredients are "wild almond leaf extract, sodium chloride (salt), calcium chloride and preservatives." I was worried it might affect PH -- as on the box in Thai it says it "lowers hardness of water to help neutralize PH."
But last night I did a test with a pail of water, and it didn't seem to noticeably affect the PH at all according to Tetra test kit (even when I purposely overdosed the water).
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But again curious if you get any PH swings when using regular Indian almond leaves.
PH swings will occur with tannins when you have low KH (buffering capacity), like around 4 degrees. If you have high KH, like 8 degrees, it will take a lot of tannins to bring that down. I found that it takes about 1 cup of sphagnum peat moss to reduce the KH from 8 degrees to 4 degrees of 24 cups of water.