Adding Beneficial Microbes to DWC Solution


Well I’ve got 4 very nice plants growing in hydro right now.

These plants (2 Jamaican Pearls, a Big Bud White Widow Cross and a Sweet Skunk) sprouted on June 9 in styro cups sitting on an east facing window sill. Once they had a nice tap root and some sturdy hair roots–June 19-- I transplanted them into hydroton and DWC hydroponics. They are growing very quickly with realy nice rich green top growth. The root systems are doing very well, a couple of them being as long as the plants are tall. There’s no slime or sign of disease, only an ocher patina from the Fox Nutrients I’m using.

So why post this? Some of the lower leaves have turned yellow in a fashion I can’t compare to any disease/treatment guide I can find. I’ve added 3 tbls of H2O2 to the 3.5 gal reservoir mostly on general principle. That brightened the roots and even richened the green of the top growth but didn’t do diddly for the yellowing of the leaves. I’m hoping someone can identify the source of the yellowing. And also provide a little advice about their experience about the quantity of Great White microbe additive they have used per gallon.

Many THANKS and keep on Toking!



Hey @mchopperpilot,

I use Great White mycorrhizae, it is great stuff. I follow the directions, or even use much less. It is full of good micro-biotic spores, so even a little will grow in a healthy soil or reservoir. Just don’t inhale a lot the powder, it could give you one heck of a sinus infection.

As far as your leaves are concerned, they all look like a pH nutrient lockout situation. What is the pH, the nutrient concentration in EC or PPM, and what is the temperature of the reservoir?

Happy Growing,



Hiya, MacG,

Thanks for getting back with me so soon. I’ve been using Fox Farms nutes and following their feed/water schedule for the most part. Because of previous experience with nute burn I’ve been keeping the ppm @ 3/4 of their max recommended level. The level was 864 ppm this morning after a feed yesterday that brought the level to 112 (x10) ppm.

The Ph this AM had crept up to 7.3 but has been pretty steadily maintained at 5.8 - 6.3. I changed the reservoir last Friday (I wash out every 2 weeks) and always start at 5.8. So today has been the first time I’ve had to adjust the Ph since the solution change.

Solution temp is a problem area for me. It has gotten as high as 76.3 with these plants. But the first thing I do every AM is ice (I can’t afford a chiller) down to approx. 68F and add either frozen chill cells or frozen water in a 10 oz soda bottle to help hold the temp down. With a few exceptions that will hold the temp to less than 73.5F the next morning. The enclosure temp (I use LED lights) is 76F +/- a fraction after I set up a 4" and a 6" duct fans of intake and a 4" centrifical outlet and a 6" circulating fan inside. The RH holds at 52% with a cool mist humidifier going 24/7 and 48% without the humidifier.

Beyond this I don’t know what else to tell you.

So what would be probably the best course? To go ahead flush/rinse and either set the solution at 50% nutes or maybe just layoff feeding until things stabilize? These plants really are growing to the point of noticable difference on a daily basis. That’s what put me in a quandry about what is ailing them.

Thanks a ton for the help, Bro.

Keep on Toking!


A couple of things that might help, although 1100-1200ish PPM is very often not too high with many strains, it is on the higher side of the nutrient concentration scale. A stable pH is often attained as low as 250-300 with most hydro nutrients and most adult plants do well at around 600 PPM. I normally shoot for 400-800, depending on the nutrient I’m using, but almost never higher than 800.

Also, with higher temperatures, higher nutrient salts in the water will mean the water is able to hold less oxygen. And so lower PPMs is usually a must if temps are at the higher most tolerances.

I’m suspecting most of the leaf damage is from nute burn as your ph doesn’t seem to be too far out of range for too long.

And are you using zero or near zero PPM water to start out with and for topping off your reservoir?


I always start with 0 ppm water either rain water, distilled or spring water but never tap water. The commercial water here has so much chems in it that the chlorine will burn your nose if you sniff it closely so I won’t even use it to flush with.

I had laid off feeding and am just letting the plants suck up the residual nutes but the TDS was not going down. So today I changed soulution, cleaned everything down and sanitized with boiling water, thoroughly flushed the netty pots, hydroton and root systems, and then refilled the reservoir with 5.8 pH balanced water and swapped out the 7.8l/m aeration pump for a 16l/m pump. I didn’t add any nutes at all looking for some advice on how long to hold off on feeding and what would good level to restart feeding at.

Peace and Toke On.


After a flush like that you should be able to go back to a good regular ppm pretty much right away, as I said above, I like a about 600-800 ppm, I usually shoot for 600 ppm with a full reservoir and if due to evaporation and the plant uses more water than food, it usually won’t get above 800 before I end up adding more water to get it back to 600.



Thanks for the info. You didn’t say but I assume you’re using ILGM nutes?

I’m trying Fox for this grow and it isn’t as concentrated as the ILGM stuff. Anyway I’m starting a bit conservatively at 500 ppm and I redosed with White Shark microbes at 60% of recommendeed concentration. All the plants have really nice, full, white root systems which is surprising after all the bad things that have gone on. I also added 2 tblsp of 3% H2O2 to pretty much clear up any contamination or unwanted bacteria. Only time will tell now, I guess.

I did want to ask about the hydro solution. The temp creeps up over night to 73 - 74F and pH will creep up to 7.0 +/- a couple of 10ths. Not being able to afford a chiller I’m using cubed ice and soda bottles of ice to try and keep it in check. So far I’ve been able to keep it within a range of 68F and 73F although it did get as high as 76F once. As long as I’m using the ice and frozen bottles I don’t have to 'top off" the solution. Actually I wind up having to siphon off solution and kep it 1 - 2 cm below the bottom of the netty pots. I also mist both the foliage and hydroton medium on a daily basis with 5.5 pH 0 ppm water. I wat until I’ve done everything else and the pH the reservoir to 5.8pH Using the ice and frozen bottles won’t do any harm will it? It take a quart container of ice to bring the temp to more than 66.5F and less than 70F.

The only other thing, and the plants don’t seem the worse for wear for it, is I’ve been running the LED lights 18" above the foliage and on a 20/4 hour schedule ever since I transplanted into hydro. Would it benefit back off to the traditional 18/6 light schedule?

Thanks so much for the help and keep 'em growing, Bro.


Misting your plants everyday, may be the cause of the leaf damage.


latewood, thanks, man.

I never realized that. I had been spraying to moisten the top of the hydroton and just got into misting the plants, too. I’ll quit misting the plants immediately. Would it help to keep on moistening the clay medium? The plants were really growing fast and great before when I just sprayed the medium with 5.8 pH’d water. But the root systems have gotten pretty extensive now so as to make any misting superfulous.


Good point, latewood.


In general when I’m talking PPMs, I’m speaking broadly and about balanced nutrient systems that are not going to be that far off from Lucas formula ratios or General Hydroponics 3 part ratios, most nutrient systems are not that far off from these ratios. Of course each system will have its own specif tweak of those ratios and their own select choice of other “additives” and “enhancers”.

I don’t necessarily see any significant problems with the system you have set up for your plant’s environment.

I would recommend not using H2O2 at the same time as white shark, you are just killing off a lot of the product. Maybe apply H2O2 the first day to kill anything that might be in the container, hydroton and/or basket, and then hours later, or the next day apply the great white to help establish a good microbe environment.


It is not a good idea to presume to know how to use advanced ratios; When you have not learned to use basic formulas.

If you plan to use GH 3-part. Do a grow using 1-1-1. Find out what the formula produces by following the directions.


All that you accomplish by spraying your hydroton is to cut off Oxygen from the root zone.


Fantastic info, guys!

I hope you can see where my confusion is coming from. There’s such a plethora of HOW TO out there that it’s almost impossible to tell the good from the bad. And that’s just from reading the manuf. labels. Some things don’t really contribute to general trend of a post like this BUT I just have to throw this joke in as it’s so appropro to the situation:

Harvard Physics Professor boards plane bound for the West Coast. As the flight progresses he notices a precocious boy of 11 years or so going through the cabin talking to different passengers. Finally the boy gets to him and the Prof. decides to not get to tangled with the boy. “What do you do?”, the lad asks. “Well, I’m a Science Teacher back East”, the Prof responds thinking to put the boy off some. “What do you know the most about, then,” asks the lad. “Nuclear physics, I guess,” the Prof. offers thinking to put the kid off with that. “Do you want to talk about that?” the older man asks. “Maybe, if you can answer a less involved question first,” says the boy. “Ask away,” the Prof. says thinking he could stump the lad and be done with him. “Okay”, says the boy, “you know that Rabbits crap little pellets while Cows drop just a big wet pie and Horses leave piles of biscuit shaped mess. Why is that?” The Prof is taken back, “You know I really can’t answer that other than to say it deals with their individual digestive systems as they have much the same diet,” he puts forth. The lad simply huffs and starts to leave. “Don’t you want to talk about nuclear physics now,” the Prof asks with a smile thinking he had pulled one over on the boy. “Oh no,” the boy returns, “since it’s plain you don’t know shit why would I assume you anything about nuclear physics.”

That’s much the same about most other info I’m finding. So I’m going to stick with you guys although you’ve probably already figured out that I don’t know shit. So please continue to bear with me even if much of what I ask seems overly simplistic. I do ask because I don’t know.

Everyone who has replied to my posts so far has been truly great and many thanks for that.

Peace and keep on growing!


Didn’t Socrates say that he was only smart in that he knew he didn’t know shit?



Amen to that!

But there’s a bunch of idiots disseminating all kinds of kaka that just puts those of us who will admit we don’t know shit further asea. It’s like the Internet validates just whatever gets posted. You can open a website posing any kind of info and if it pops up on a search all of a sudden it’s gospel on a given subject with no vetting required or provided.

So far I gotten nothing but straight skinny on this site. And, thanks for that and the amount of patience you guys have to help dumb asses like me.

BTW, the plants I started this thread about are quickly recovering after I stopped misting them and the hydroton. One plant, a Sweet Skunk, still has a couple of leaves with yellowing at the tips of the serations around the edge but that’s all. I’m still having spikes of pH from morning to morning. Usually the pH will around 7.5 when I ice the solution down in the AM. As a last step in the AM routine I take the pH down to 5.8 but it will be right back up the next day. Is this normal? Increasing the aeration pump to 16l/m has really boosted the bubbling of the solution (mine is a 3 1/2 gal bucket and I’m using a Red Frog system that’s made up of rubber infusion tubing instead of air stones for a much larger area of air saturation especially with 2 ports off the aeration pump feed each of the 2 air hoses going to the Red Frog). The aeration increase has brought the overnight temp increase in the solution down by right at 2F degrees.

Many thanks for all the help. Keep 'em Green and growing.


I was told by the guy at my local hydro store that the smaller the reservoir the more fluctuation in ph you will have but I haven’t asked the guys on the site about it, like you said there’s a bunch of not true b.s. out there.maybe one of the pros will see this and confirm or deny what the guy told me