White Powdery Mildew?

Hi guys. Been dealing with some issues for a while now before asking for help. For a while I had my RH cranked to like 60-65% because I had some dry weed hanging in the shed and I was trying to keep it relatively moist. Finally I found out that was causing deficiencies in my plants and they stopped growing completely for weeks. They are finally bouncing back after lowering RH and spraying them down for mites, but I think it's possible I have mildew in the shed. I put the RH down to 35% now and all the growth is a healthier green now except for the new growth is light green and some older leaves are turning colors and kind of dying off. I found a couple small white spots on my young autoflowers but it doesn't look like the mildew I've ever seen. Could be just another issue? But I have some white crap all over my hydroton rocks and it doesn't make sense how that would appear. I have heard of residue from tap water leaving white powder behind but this is weeks later after the rocks have already been cleaned and these rocks slowly 1 by 1 seemed to turn white. Maybe it's because the 65% RH allowed it to grow on the surface? It is not spreading anymore but really white stuff seems to be thick and I can scrape it off.

Also, can anyone tell me why my young autoflowers are turning light in color, and bottom leaves are browning at the tips? Maybe it is mildew affecting it because the water in my resevoir should be balanced perfect.

The white stuff on the hydroton is likely salt buildup. Its because the hydroton was reused from a previous grow (a drip feed type system I'll guess)? Its pretty normal and it shouldn't hurt anything.

Some info on the grow would help others help you like:Whats your pH? Whats room temps/res temps? What nutrients & what ppm? How often you feed? What system you running?

The weird thing is this is actually new hydroton. The only water it has ever came contact with is when I rinsed it with tap water to clean it before use. This is actually a DWC setup. Sorry for lack of details. I'm just more concerned it could be something else because normally the salt buildup would appear soon after the water dries on the rocks. This crap appeared weeks after. I actually have larger plants in the room I did not take pics of. They are in soil but I'm more concerned about the autos in the DWC tub. I keep pH at 5.8 and I'm feeding them Lucas formula (FloraMicro & FloraBloom). Ppm is around 500 currently. And I give them HydroGuard to prevent root rot.

I'm keeping the room around 73° F and the RH is now at 35% as of 2 days ago, before that it was lowered to 45% after I realized 65% was causing deficiencies.

But every plant in the room is almost at a stand still. Very slow growth, takes a couple days or more just for a new leaf set. At this rate I will have 10 inch tall autos when they start flowering..

The only other issue I can think of is the light I'm using. Ever since I got new lights, it seems the results I'm getting are slower growth.. I'm using a hydroponics hut X5-600 LED light. It's hung roughly 6 feet above the canopy but from that level the plants are still receiving 30,000 lux or slightly less according to my meter.

jsisko01 said:

The weird thing is this is actually new hydroton. The only water it has ever came contact with is when I rinsed it with tap water to clean it before use. This is actually a DWC setup. Sorry for lack of details. I'm just more concerned it could be something else because normally the salt buildup would appear soon after the water dries on the rocks. This crap appeared weeks after. I actually have larger plants in the room I did not take pics of. They are in soil but I'm more concerned about the autos in the DWC tub. I keep pH at 5.8 and I'm feeding them Lucas formula (FloraMicro & FloraBloom). Ppm is around 500 currently. And I give them HydroGuard to prevent root rot.

I'm keeping the room around 73° F and the RH is now at 35% as of 2 days ago, before that it was lowered to 45% after I realized 65% was causing deficiencies.

But every plant in the room is almost at a stand still. Very slow growth, takes a couple days or more just for a new leaf set. At this rate I will have 10 inch tall autos when they start flowering..

The only other issue I can think of is the light I'm using. Ever since I got new lights, it seems the results I'm getting are slower growth.. I'm using a hydroponics hut X5-600 LED light. It's hung roughly 6 feet above the canopy but from that level the plants are still receiving 30,000 lux or slightly less according to my meter.

Click to expand...

Sorry, I assumed it was used already from your mention of wash not realizing you meant initial wash, out of the bag. It's usually drip feed that get the salt build up on hydroton. Whats the texture of the white stuff on the hydroton?