Help!! Black Stuff Appearing On My Live Plants

[Dennis57]

Hi all, this morning around 7:30am. I checked my tank and noticed black stuff on my plants. When I got home 8 hours later it spread to most plants and my water wisteria looks like its turning brown.
Here's what I have-- 55 gallon with a Fluval Plant Spectrum LED light that's been working for about a year. I have Eco-Complete substrate for about a year. I started using Seachem root tabs about 1" away from my plants (1 per plant) and Nilocg Thrive + 2 times a week for the last 2 weeks.
My Ammonia-0, Nitrites-0, Nitrate-5, PH-6.7 (usually around 5 - 5.5 out of tap) I do 50-60% water changes every Saturday, on Sunday I add 5 pumps of Thrive, on Wednesday I add 5 more pumps, and 3 times a week I use Excel.
MY LFS (who I been using for years) sold me Alkaline Buffer and Acid Buffer, I use 1tsp each right after the water change 9Mix it with water before I add it back to tank.
Any one know what I can do? I,am lost. P.S. I tried to wipe it off with my fingers and a toothbrush, no luck. I do not use co@, iron or potassium. Thanks for any ones help on this

 

[bizaliz3]

Looks like it could be diatom algae. Can you gently rub it off with your fingers?

EDIT NEVER MIND, I see you mentioned that at the end of your post. I missed that sorry.

 

[Wraithen]

You have green spot algae in addition to the darker stuff. That's usually a phosphate deficiency, which your plants are showing.

The darker stuff is black beard algae which is a symptom of too much or not enough almost everything. You're also showing nitrogen deficiency.

Up your ferts. Should be all you need.

 

[Dennis57]

You have green spot algae in addition to the darker stuff. That's usually a phosphate deficiency, which your plants are showing.

The darker stuff is black beard algae which is a symptom of too much or not enough almost everything. You're also showing nitrogen deficiency.

Up your ferts. Should be all you need.

Should I add more then 5 pumps of Thrive? More then twice a week? As far as iron and Potassium phosphate, should I add that? Any idea how much for a 55 gallon tank that has about 2 dozen plants. Thanks

 

[Wraithen]

Should I add more then 5 pumps of Thrive? More then twice a week? As far as iron and Potassium phosphate, should I add that? Any idea how much for a 55 gallon tank that has about 2 dozen plants. Thanks

I would just dose more frequently. 3 times a week instead of 2. Thrive should have plenty of NPK in ratio so the extra dosing should help. I would definitely be dosing iron. Dose it on days you aren't dosing the thrive, or at least offset by 6 hours minimum.

 

[Dennis57]

I would just dose more frequently. 3 times a week instead of 2. Thrive should have plenty of NPK in ratio so the extra dosing should help. I would definitely be dosing iron. Dose it on days you aren't dosing the thrive, or at least offset by 6 hours minimum.

Thanks for your advise, I will give it a try

 

[-Mak-]

You also seem to have magnesium deficiency. A lot of the time liquid fertilizers including all in ones don't have a lot of magnesium or calcium, I'm assuming it's because they ride on the assumption that you already have some in your tap.