If you notice white salts building up then the only cure is adding plain water to help dissolve and flush out the salts. Water absorbs salt, its probably going to take a lot of run off, let the plants almost dry out and just blast them with plain water then next time they dry go back to normal feeding. In coco you also want to make sure its not getting dry enough to salt up while the plant is alive, you wanna keep it moist to prevent that salt from solidifying.
Smaller pots will be less forgiving especially if you let them dry out at all with heavy feeding, the nutrients will just crust up. IF you keep coco wet it'll be good as long as you don't over feed and over water. If I had the headroom and wanted to spend a few grand I'd do flood tables and drip irrigation but for now I'm keeping it stupid simple haha. I water using a 32 gallon brute bucket on rolly wheels and a 5 gallon measuremaster bucket.
19L pots are big, am not sure if you can water every day. If the plant is big then probably yes. Water every 2 days or every day and with good runoff since you havent done it. Should fix itself slowly. I wouldnt panic and do some crazy flushing.
