pale and dark

It follows reason that if there is an imbalance in the fish tank with the nutrient dosing, that the water I take out and give to houseplants will have the same imbalance. I noticed recently that the anubias lanceolata in the tenner has pale leaves with darker veins, and it looked like the java fern was starting to develop that, too. So I dosed magnesium in that tank again.

And now just a few days after doing water changes and watering houseplants with the old tank water (as usual) the younger, lower leaves on my avocado plant show similar symptoms:

Upper, older leaves aren't as affected:

Hm. It looks like I should be dosing the magnesium once a month, or once every other month.