Thanks for nice explanation Darrel. Just to clarify I was not talking about Potassium deficiencies but excess of it. I decided to cut doses of Potassium as a few members of another forum confirmed that reducing Potassium concentration in their tank resolved their problem with stunted or twisted growth. I've not been dosing Potassium for more than a week now and I have not seen one stunted growth yet. I can't say that it won't happen again but so far I can see some improvement so I will try to keep it that way. After 7-10 days between water changes my glass was spotlessly clean and never had to even wipe it off. After dosing some additional Iron (only about 2ml/day) my glass became green after 4 days. After 7 days I had to scrape it off as it looked disgusting. Now stopped dosing it again and my glass is clean again. As I saw few people having the same problem with stunted growth I will keep the post updated. Let see where the experiment will take me. This week I will also be mixing my tap water with RO to lower my KH, GH and most importantly PH.