Plagued By Root Rot

Indoor Grow
Method: Hydroponics
Medium: Hydroton
System: 2 DWC buckets
Water Source: Tap Water
pH: 5.5 (constant read, calibrated 3 days ago)
Tap Water PPM: ~300
Plant Age: 5 week old clone, Day 4 of flower
Nutrients: Pure Blend Pro Bloom and Grow (50/50 mix) and Hygrozyme
Current PPM: Was 1,000, 750-800 since root rot
Lighting Source: 1KW HPS for flower, 2 50W CFL for veg
Temp Ranges: Day- 83-89° Night 73-78°
Reservoir temperature: 70-74°
52% RH
Light Schedule: 12/12 in flower, 24 in veg
Ventilation: 200 CFM extraction, filtered 20" active intake
Presoak Medium: Yes

Details:
I have two flowering plants at day 3 and a mother in DWC and 2 clones in an E&F stystem. The E&F plants are fine but ALL my DWC plants keep getting root rot! I just changed all their res's, scrubbed everything with bleach and hot water, rinsed thoroughly, and also sprayed the slime out of the roots with pHed water. I did the same thing on Sunday, and it came back in a day.

I know my temps are on the high end of the spectrum, but I always understood 75° was the danger zone. The res on the flower side did to 76° once but it has stayed consistently at 74° for a while now. My equipment is clean as a whistle. What am I doing wrong? If its the temps, what is the best way to get them down?

Oh, and I don't have pictures. The plants look green with yellowing starting at the bottom and curled burnt tips throughout. Top leaves look green but are starting to curl. They don't really looke that bad yet, but they definitely are not good.

I have never personally grown with hydroponics but I will apply basic science to this the best I can.

1) Do you expose the roots to air often and is the air being circulated fresh?

2) Do you use latex gloves or disinfect your hands before touching them? - wash for 60 seconds with warm to hot water and soap then put on gloves....

3) Is the water valve or the pump self feeding or hooked up to a line in your house?

Those are my best guesses. Unless the nute sources you drop from are slimy too.... :weedpoke:

OK so I just went to shut my curtain and found the air temp at 90° and the res temp at 79°. Is there anything I can do about it?

You can fill small soda bottles with water and chill or even freeze them and add them to your res, although in a very small res this may not work.

No matter what, you should try adding MORE oxygenation. If you have one airstone, add 2 more! The zyme products are fantastic but really need a good, well-aerated environment to work... as a matter of fact, so do the roots themselves! ;)

I have these big air stones running on an industrial pump to aerate the buckets. The airs stones cover about half the area of the bucket and provide plenty of air. I used a frozen bottle of water to chill the res last flower but the water would melt within a couple hours.

I think it is just plain too damn hot outside to flower inside right now, even in my cool basement. My 1KW HPS is making it impossible to deal with the temps without some kind of AC unit. I am just going to have to move the two plants back to veg and try again in a month or so. :(

If you are not already running your lights from about 9pm to 9am I'd change that right away; same goes for an air-cooled hood.
I feel your pain; I just dropped $200 on a cheap imported no-name portable a/c unit... the 'good' ones were like $400! And that's in a basement, running at night.

Here's an idea: High temperature shutoff. You plug your 'main' light into the unit, which has a thermostat that you can set to 85'F. When it trips, the power is cut to the socket. You keep as backup a couple flourescent fixtures flanking the edges of your hood, and those stay on during the timed 'on' period to maintain photoperiod without adding significant heat.

Also try switching your intake to come from within your cellar if it doesn't already, or if you have a cool crawlspace duct air from that. For more ideas on cheap passive cooling, check out sites about passive solar home construction, the concept of the envelope house, and thermal mass cooling systems. Often these include a basement room full of large rocks. I've toured a couple, and intend to build one someday. They are fascinating.

I run my lights 8-8 and its still too hot. Even at night its almost 80° right now in mid July, so when that 1KW light turns on in my tiny little 5x10 grow room and the night temp is at like 78°, its just too much. In the fall it will be a different story though, and I will have some huge plants to yield huge buds, but it just sucks waiting that long. :jointsmile:

Res. chiller .

I'm a tight ass and won't buy 1 myself .

I've been doing soil / soiless grows in the summer , and hydro in the winter because of these same problems w/ rot .

Crispi :stoned:

Try adding SubCulture to a soil grow, with lots of perlite and good frequent waterings- that would be my choice were I to suffer that problem. Also, Serenade can be added to your res.
Last, the NFT style is an interesting choice for a situation like yours. The constant aeration and washing action over the roots, plus the fact that the water is constantly moving across a filter (you can add extra filtration to help remove dead shit and pathogens), helps prevent buildup of dead cells and rot from setting in.
Hope that helps?