Optimal DWC water temperature to fight green algae; 58-60F too cool?

[MajorTom]

I've been having a (blue?) green algae problem using Hydroguard and keeping my water temp around 66F. Finding out now that Hydroguard doesn't protect against this type of algae and that it won't grow under 60F. Does anyone have any more info on this? And is 58-60F too cool?

Using GH FloraShield now and doing my best to close up any light leaks. Is that the most I can do? If 58-60F is too cool, then how far down can I set my water temp?

Thanks!

[9fingerleafs]

i have no experience in DWC but to my understanding your problem is the light is getting into the roots, thats why its getting green only on the top, light promotes chlorophyll production to photosynthesize.

[alltatup]

Hi tom, this is ground control. I agree with 9fingrlfs: you probably have light leaking into the reservoir. Can we see a picture of the setup?

[DoctorJohnson]

That's cyanobacteria, a.k.a. blue-green algae. The way to prevent and control it is to keep out light, keep the water cool, and lots and lots of water circulation. A $25 submersible aquarium circulation pump from the pet store in your reservoir will help a lot. Many have venturis that suck in air and oxygenate the water too.

It's kind of gross stuff (my GF used to call it "cyanoslime" when it got in her fish tank) and it has a funky, earthy smell (from a chemical called geosmin), but it's not really evil. (It's also probably one of the oldest life forms on earth, so respect is due. )

[MajorTom]

Thanks everyone for your comments! I've got the water temp set at 64F and some good bubblers with a strong air pump; and I'll look into the circulation pump.

On the light, rookie mistake not to pay more attention to the light leaks coming through the lid from the very beginning. I've made a patchwork of thick duct tape to cover up as much as I can; and I've replaced all my clear hoses with black ones. Next time I'll cut out some snug fitting, thick light stopping plastic lids to cover the baskets and other things leading into the reservoir to keep out the rays.

On the algae, thanks for the info. By the time I checked back in on the plants, a lot of damage had been done. No more high expectations on this run (haha).... but still trying to see what can come out of it.... It's a BlueBerry auto that was just beginning to make its transition. I did some light lst on it to expose some of the inner nodes (which actually looked pretty good) -- so we shall see..

Thanks again!

[alltatup]

I had a terrible algae problem on a previous grow, and while it certainly slowed down the growth, I harvested pretty good bud. The problem was light leaks into my reservoir.

[MajorTom]

Thanks Alltatup!

I've been having to leave mine for 10-12 days at a time lately in a closed box in an attic room. The room has poor ventilation. I've got good ventilation on a temperature switch pulling cool air (via portable A/C unit) through my closed box keeping temp/hum around 75/47F. In addition to the algae I'm wondering if poor air quality might be another factor causing slow growth and considering an air exchanger to get more fresh air into the room. Any thoughts on this?

Also, I noticed you had a Micro grow going. How tall is your setup? I'm working with total 3.5ft height w/ a dimmable LED that pulls 200w. I can add supplemental lighting from time to time but very sensitive to heat buildup. My girls are pretty short and have been slow growing at about 6-7" after 43 days. I was keeping the lights at 23" w/ full blue and partial red. I just moved them down to 18" with 80% blue and 100% red as they seemed to be transitioning into bloom. See pic of setup above. Anyone have any comments on this?

One more thing, does the yellowing of the leaves in the pic above look like nutrient burn in addition to the root problem?

Appreciation....

[DoctorJohnson]

Just really getting in and blocking out all the light should do it. If damage has been done, I doubt that it was the algae. Mostly it just wants to eat your fertilizer. Give the roots a good rinse to break free the cyanoslime and you should be good.

[Grinder]

Is your reservoir transparent? From those pics it looks like you have a clear container. If so then that is your problem.

[DoctorJohnson]

Good eye and good point. My reservoir is a clear plastic container that is lightproofed with foil and black adhesive shelf paper.

[MajorTom]

It’s clear but wrapped in the same semi insulated reflective material as the walls. It’s got these ridges however that might be letting some light in. Will check. I like the idea of adding a solid black layer too.

[abadtrip]

Yea paint it black

[MajorTom]

Sounds good! Learning this lesson the hard way.. ;-/

[DoctorJohnson]

> Learning this lesson the hard way.. ;-/
Your learning lessons the way we all do, and that problem isn't very serious and is easy to correct--nothing like "OK, next time don't let the four-pound lamp fall on the plant to crush and burn it."

[Sonnyhad]

I'm just starting a rdwc grow first one also in water. It's been a rough go so far!

[MajorTom]

I hear you, Sonnyhad. There's little margin for error with my setup because every set of decisions I make has to be right for the next 7-10 days or so. If I get something wrong, its compounded. Hoping one day I'll open up my little box and see my plants smiling back at me....

[MajorTom]

The support helps a lot. This can get pretty frustrating and I've already had some "moments". I do not consider myself a natural gardener so this is even more challenging... It's more of the technical side of things that is so alluring...plus benefits.

[DoctorJohnson]

DWC has it's challenges, but when you get it working, the results are awesome. I'm inclined to agree with site maven Nebula that it gives the biggest return.

[alltatup]

Tom, I hope that you fall in love with your cannabis plants: that's what happened to me. It's an honor for me to cultivate and harvest them.

[alltatup]

Tom, my first thought was that the burned leaves looked like really bad nute burn that wasn't corrected.

Poor ventilation is not good for cannabis plants: air circulation is crucial. I think you're gambling if you have to leave them for long periods of time. Not the best conditions for tending to, taking care of, and keeping your eyes on what's going on with your girls.

I'd also suggest that you do some serious reading about what the plants need and how to supply that. You have to tune in the temp, humidity, air circulation, etc. according to the environment you live in. But even though this site is called GWE, it only gets easy if you know what you're doing.

For example, you have to be able to recognize the very first signs of nute burn on leaves, and adjust accordingly. Your plants got bad burn because that didn't happen. Most of us have been through these tough lessons, forked out $$$ to fine tune the growing environment (I dread to think of how much I've spent to get my girls in the right conditions for where I live), and learned to do it better. While cannabis plants can thrive on their own growing in their natural environments, when we bring them inside, there are a lot of different factors at play that we just plain old have to master. I'm still in this process; been growing for 21.5 months; 2 yrs. in July.

I have two grow boxes: a big one (BCNL RoomMate, excellent box) and a small one (a super closet that I would not recommend to anyone) that I only grow short plants (short Indicas) in. They have around 30" up to the light, so for the small grow box, I switch them to flower quick. I also included a pic of a sativa grow in the Roomie definitely outgrew the box.

[Sonnyhad]

Excellent advice alltatup!

[MajorTom]

Thanks for the info, Alltatup. Was afraid it might have been that. Normally I'm around 'em for a longer period of time so I get to watch them and look for the signs, make a correction and such; but lately it's only been a couple days in then back out again. Fortunately, the mechanics of everything (except for the light leaks) have been running very well. I can see now the BIG mistake on being too heavy on the nutrients. I'm very meticulous with my measurements and record keeping, just too heavy on the throttle this time around..

And btw; those are awesome pics! Looking forward to the day....

[alltatup]

Thanks Sonny and you're welcome Tom.