Great White beneficial bacteria in DWC


i was having problems with unhealthy roots in my system so I started using Great White. Ive noticed that there is a film of sediment on the bottom of the reservoir which has to be the great white. is this supposed to happen? I’m trying to figure out if this is a sign that by bubbles/aeration is not powerful enough or that i need to install a water pump to circulate the water. my setup is a 50 gallon tote, with probably 40 gallons of water. two 17watt airpumps with two airstones. water temp stays between 63-69f, ph 5.6-5.8, nutrients are floranova grow running around 400 ppm as im in early veg. its probably noteworthy that this is my first hydro grow so i am still learning.


Hey @MacGyverStoner or @latewood can I get a response?


It’s hard to say what the sediment is actually from. I use great white and have not had this problem.

The fact that you started to have unhealthy roots in the first place, even though temps are under control, is probably a good indicator that your dissolved oxygen is too low.

A lot of people don’t believe in using beneficials in DWC because they don’t think you should need to culture bacteria or fungi in the root-zone and it might get out of balance, also the fungi won’t really survive with too much water and no soil to grow on or in. Again, I have not had this problem, but I do use great white very sparingly and I do believe some of the fungi will populate the root mass in the media above the water line.

You might want to look into more, or different air stones. Aeration is not necessarily best only with super fine bubbles. A super fine bubble stone might be too restrictive and not be letting a very high volume of air through. Also a lot of dissolved oxygen comes from the water movement itself at the surface. So you really want all your water surface to be disrupted with tons of bubbles and water movement from the air rising rapidly through the water to the surface. The movement at the surface of the water with the air is as important as the bubbles themselves.

I say focus on the more air and more movement because a 17 watt air pump sounds like it should be enough for your tote. I’m assuming it is a basic DWC with the net pot suspended above the single reservoir, and you are not using a under current recirculating system, as you didn’t mention it. Also a undercurrent system would certainly need a water pump to recirculate the water from the main reservoir to the DWC undercurrent container.

Hope this helps,



By the way, just to clarify, the undercurrent water movement will not help with dissolved oxygen, the movement I’m talking about is the surface action where the water at the top of the surface is itself coming in contact with that air above the water. In other words, splashing is important. Some people do use water pumps to create a waterfall inside their reservoir to help with the “splashing”. However submersible water pumps can add heat to the reservoir temps, so this is not necessarily better than air stones.



2 things I need to add.
1, When noticing an issue with your roots; It is best to seek advice before you buy and add something to your reservoir. It is better to figure out what is wrong. Now by adding Great White?, you have clouded up[ the event making it harder to diagnose.

  1. IN big tubs I used to use 12-14" airstones/bars. They work great.


@latewood was there a second part to that? The only thing I could think of besides more air is that bad bacteria must be harming the roots (they were turning brown and stringy/weak) looking like root root I thought the plethora of beneficials in GW would help. I think that great white was settling into the bottom of the rez making a thin brown layer due to no under current.

@MacGyverStoner not all of the roots are looking bad due to the great white, but the floranova organic nutes i believe is what is helping the bad bacteria stay alive in my system even with the great white fighting it. I did not know upon buying them that organic nutrients are not good in deep water culture. With that knowledge yesterday i purchased junge juice grow from advanced nutrients. At the same time I bought EWC and molasses to use with the great white I have to brew the “heisenburg tea”. Tomorrow night when the brew hits the 48 hour mark I’m going to dump the rez, sterilize everything, switch to the synthetic nutes at half strength, and follow the tea application schedule. The tea I have read countless success stories from people who had it much worse than me so I have high hopes for it. ALSO an important thing to note is that I DITCHED the 50 gallon tote and swapped it for an 18 gallon that I estimate has 15 gallons of water in it. Now the ratio of air to water is MUCH better. I have about 35 watts of air pump to 15 gallons of water.

I only have 3% h202, what is the best way to sterilize /clean the roots before putting them in the new rez with the tea?
@MacGyverStoner & @latewood thank you


I use FloraNova in my DWC, almost always have and it is pretty much the only nutrient line I use, also I pretty much only grow in DWC and no other form of growing, with the exception of keeping mothers alive in a ProMix and Coco blend of my own making, and I use the same Flora Nova on them.

I’d bet, just the change to the smaller reservoir and higher aeration ratio would make the same improvement even without switching to “synthetic” nutrients.



What? No root pictures


Also EWC tea is a “organic” nutrient. And Flora Nova basically has has earth worm castings in it.

The great white is supposed to do about the same thing as adding a “tea” to a DWC, just adding lots of aerobic bacterial spores and “good” fungi spores.

Adding a bunch of H2O2 in the res is going to kill a lot of that stuff off. Either you go totally synthetic, no beneficials and no teas, because with only synthetics they don’t really have anything to live in, and you use a lot of H2O2 or you go organic and with beneficials and with teas and such and something like Flora Nova. It sounds like maybe you are mixing and matching too many different things together.



Does anyone out there have any idea about hooking a small medical oxy machine into the air supply on my DWC set up for 16 plants i use 4 blue stone? air pumps dual diapham. .But thought it mite enrichen the water better . But i also have well water and am worried that it could cause nute lock out … Any one with any thoughts on this

Useing medical oxygen with DWC?


I don’t see why not.

Many commercial hydroponics systems use electrolysis or ozone generators to infuse concentrated pure forms of oxygen into the water.

Something to consider, however, is that highly concentrated pure oxygen will likely cause rubber and plastic parts to maybe become dry and brittle and wear out faster, especially the rubber diaphragms in the air pumps.

As far as the well water is concerned, it all depends on how hard the water is and if you can keep the pH at 5.8 for hydro, and especially for DWC.

Happy growing,


Useing medical oxygen with DWC?

While reading posts on DWC, I see your use of Floranova. Any other nutrients, besides ILGM’s, that you would recommend as necessary?
Thanks for the info.


Advanced nutrients jungle juice with pH perfect technology. I’ve never had happier plants, and it keeps the pH in the right place which = less maintenance. Also you can find grow micro and bloom on amazon for under $45 all together


After reading about the nutes, I believe you are correct in pointing out the benefits of a 3 pack of nutrients for the grow. I am admittedly a novice for an indoor garden, and I need to keep it simple to help resolve any difficulties.
When you see AN has so many choices, with names promising even bigger, juicier harvests, it’s hard not to be confused.


I suppose you could say AN has a lot of different choices but realize they all have different advantages or purposes. There is a normal jungle juice(not pH perfect), and there is the new pH perfect jungle juice. This is a 3 part base nutrient (although Lucas formula only used micro and bloom). Recommended additives are B-52 fr vet stage (vitamins- not necessary) and then big bud for bloom (also not necessary)


This might be worth some research ?


I had a pretty bad root rot problem a while ago I cleaned my airstrips and started adding great white within a week and a half my roots were bright white and the plant doubled in size great product. I add 1/4 tsp per gallon each week when I do my water/nute change