Potential Iron Deficency

how's it going guy and girls

noticed one of my seedlings was looking a little sick so i did a little research to gt to the root of the problems.

im running a 16/8 light cycle for them atm
i have a 400w hps light
using 50/50 perlite, potting mix
i haven't added any nutrients yet other than ph down used to correct my high ph tap water.
the ph down mix contains 20% phosophric acid
i let the water sit for a few days in a bucket to get it to room temp and let all the nasties evaporate.
the ph is quite consistantly between sort of 6.2 - 6.8

my conclusion is that from correctng my tap water i have added excess P to the soil while leting the FE level decrease.

what do you think? any ideas or comments

i was thinking of adding some organic fertilizer to it but thought that might toxify the soil so hmmmmm second opinions?

here is some photo's to help



any help would be vey much appreciated.

Peace
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In a Iron deficiency, or "Iron Chlorosis" the leaf tissue will be pale green/yellow while the veins will remain fairly green. Your issue appears to be the opposite which leans more toward a macro-nutrient def. such as N, P or K. The minute quantities of phosphoric acid that you use to lower your pH are unlikely to have caused a P imbalance. I would start by applying a pH'd solution of fertilizer in a 2-1-1 ratio as it looks plenty mature enough to start feeding and no, the organic fertlizer will not "toxify" the soil. The ratio of perlite you have mixed in the soil may be a contributing factor as 50% sounds very high, also considering that potting-mixes all contain perlite to begin with. Perlite is a inert ingredient and is simply there to provide good drainage and ample oxygen for good root developement. If this was my one-and-only-plant I would buy a good quality potting soil such as Fox Farms Ocean Forest and simply re-pot the plant with no amendments. Then, wait 1-2 weeks before resuming a fertilization schedule and it should slowly recover.