Ayuda crecimiento estancado DWC

I started to get these spots on the leaves, I removed them, currently there are new leaves that have stagnated in growth and the same spots are coming out again. I thought it was a calcium deficiency, so I emptied and put in a fresh nutrient solution with osmosis water (17 LT) (ec 0.0.). Supplement with Sensi Cal Mag to raise the ec to 0.35, then I place 15ml of rhino skin to strengthen the plant against pests and heat (it does not modify the ec), I also apply 15ml of B-52 (ec 0.40), as a base fertilizer I use Only Grotek tek Grow raises the ec up to 0.8, after that I raise the ec up to 1.0 with monster grow, I also use Great white myco. I handle a pH range of 5.57 to 6.15 and I am varying in that pH range, my grow room is kept between 25 to 28 degrees maximum. Humidity is 58% to 65%. All the plants are in the vegetative stage, this is the only one that is giving me headaches, I forgot to mention, when this problem arose the roots were stagnant in growth, after changing the nutritional solution they began to grow again at a better rate although a little slow, but the top of the plant comes very slow. The nutrient solution stays between 22-26 degrees, I can't lower it more than this. The lighting is LED CREE CXB 3590 320W at a height of 50cm. Also apply a fungicide on Sunday to see if it was a fungus, apply a folial application to the roots and leaves just in case. Reading in a Yankee forum I found that it could be phosphorus deficiency but I doubt it. Genetics is a CHOCOLATE MINT OG from HUMBOLDT SEEDS. I leave the photos of the spots that are driving me crazy and I hope they can give a hand.

Hey man. Looks like you maybe over watering it. Get a meter and check it. Soil should be in the middle

Just jumping in to comment, I was reading and it could be a phosphorus deficiency, but I don't think so. I only use Grotek's Tek Grow as a base, and I also reduced the power of the LED (Cree CXB 3590 320) which is at 50cm. I can't get the water temperature below 26° / 27°, and I'm pointing to this as the cause of the problem. I really appreciate your help!

At first, the root zone had stagnated, but after changing the nutrient solution and adding HYDROGEN PEROXIDE to it, root growth started to progress, albeit slowly. I bought Sensi Cal Mag out of fear that it was a calcium deficiency and made the nutrient solution from reverse osmosis water. The plant's growth is slow; today I did a foliar application of fungicide on the plant and roots. I hope this resolves the issue; I look forward to your comments, colleagues.