Yes it’s a very expensive source of nitrogen too, I would rather avoid it if possible. I’m going to go with sulfuric or citric acid to try and keep all my n/p/k ratios balanced
I wanted the choice between the phosphoric acid in the Cyco brand I use and nitric acid.
Here’s an example. I hit week 5 of flower this run and noticed some yellowing but didn’t jump on it fast enough. It would have been nice to add the nitric acid as ph down just to add a little bit of N. I didn’t want to dump my tank yet, as it had good ppm left in it, but most of the NPK gets used up first, so I could have waited a few days on a res change, while topping up with nitric acid to get extra N, instead of just boosting P like I did.
I found a 2.5 liter bottle for $60-70. It’s 70% acid so cut it in half with water. 5 liters of ph down for $60. I pay about $50 for the 5 liter jug of Cyco.
I’m sure it’s not for everybody though.