White mold/fungus! yuk!

Discussion in 'Hydroponics / Aeroponics' started by Jipc, Apr 26, 2009.


    Jipc Active Member

    Hello everyone! First time posting hope you guys can help me out. I have done quite a few crops in soil with a few outdoors. I decided to go hydro cause well... I moved to the city and with dirt is well dirty:-o

    I posted my problem in the plant problem section but I'm think this is more where I should be posting as this is where I got most of the info to go hydro!

    so here's the skinny:(Im copy and pasting for ease!)

    White mold/fungus issue!
    here's the deal

    1. Problem : white mold or fungus on top of growing medium and in the drain holes of the pots

    2. Growing medium: Rockwool granulate in about 3" pots

    3. Lighting: indoors under 250 HPS 24/7

    4. Water schedule: They were being watered by flood and drain every 2 or 3 days as needed but now I am just dipping the pots in the res for a few secs to soak enough water so they are on the brink of drying every day I feed with Canna Aqua using atm 390 PPM Vega with 30 PPM epson salts every watering.

    5. environmental controls: constant occilating fan on the plants max temps 81F lowest temps 68 F with fresh air entering anytime temps hit 80F MAX humidity 40%.

    6. Age: Plants are about from 6 weeks to 3 weeks old all in Veg

    pics below



    Im sorry for the picture quality this is like the best of 30 pics even ><.

    For the details.

    My Res is never over 77 F but it is just sitting under my ebb and flow table (no lid but no direct light either) I have some sort of clear scum stuff floating in the rez I treat my 30 gallons with 45 ML of 35% H2O2 every 2-3 days. the scum tends to cling to the air bubble on the surface made by my 12" air stones. if I apply H2O2 directly to it it barely fizzes. Not sure if this is related to my mold on my growing medium as that is my real concern.

    This mold does not seem to effect my plants in fact it seems to try to avoid the roots and stem( as sort of seen by my terribad pics.

    I have added styrofoam plates to cover up the tops of the pots this has had zero effect. I dont feel it feeds on light as I have the same stuff growing in the drain holes with no light exposure.

    The only source of this white mold/fungus that I can think of was when they were seedlings I had a natural seasponge giving off humidity and I saw on it the other day som white spots.

    Thanks for any help


    I was looking at my res a little better and I discovered that my water pump filter was FULL of the slime that was floating in bits in my res. I pulled off the filter and cover and dosed it all with a ton of H2O2 and I will rinse it out and then hit it with a bleach solution. I also dosed my now about 25 gal res with 60 ML of 35% H2O2 to hopefully kill anything else in there I will let it dissolve out for about 16 hjours or so till I give anything else more water.

    Either way I dont feel this is the same mold/fungus though on my rockwool ...but it may be......

    any suggestions would be appreciated! :smile:



    i had this problem before, i found out that the plant wasn't taking up enough water and was sitting in the soil. soil started growing mold very fast.

    thanks for the response.

    ok Ill see if the plant kinda "grows" outta it then. The larger plants I have don't seem to have as much of it I hope thats the problem :smile:


    check each day to see if the medium is still wet


    well Im only watering when the plants are "crying" now the pots are basically no wieght what so ever. WAYYY dryer than any soil Ive ever done lol.


    water them and see how they drain, check also to see how long the water is in the pot for

    since this problem has taken off more I have changed the way I water. Im in a ebb and flow set up but with my plants different sizesd I tend to water certain ones more often by hand. I was watering by pouring water from the top of the rockwool letting about 10% or 15% runoff happen, but when I was doing that it would take about 3-4 days for the smaller ones to dry out before I could water them again. So when this mold/fungus took hold I started letting the pots dry out even more to the point of basically TOTALLY drying out and then just dipping the bottoms of the pots in the res for about 5 to 10 seconds. just enough so that the pots gain some wieght and are drying out after one day.

    I think I am screwing with my plants too much though with all this watering crap. I should be ble to water once every 3 days imo and be fine just this damn mold/fungus ><


    So anyways there it is lame white mold/fungus growing on my Rockwool.

    Thanks in adavance!!

    On a side note I am not liking Canna Aqua with my 200 PPM municipal water >< Im fighting what seems like Mag def so Im having to suplement with epson salts and tats proving to be a pain as it doesnt seem I can add the recommended 1/4 tsp per gal or it skyrockets my PPMs I plan and cant wait to change to a lucas formula or just use flora nova ><

    fighting the white!
    GoldenGanja13 likes this.

    Will5437 Active Member

    I have a simmilar problem. I am planning on taking my cubes out into the sun when it gets sunny, and waiting for the tops to dry off. Then I will try to get the mold out, and keep my watering cycle down.
    Mr. Smithh

    Mr. Smithh Member

    This is the same crap growing on my grodan starter cubes....what is it?......can it be killed or is it something that can only be supressed? thx

    ZilDaN New Member

    I hear a lot about this problem with white mold and/or fungus. Other than throwing in a bunch of harsh chemicals like bleach or hydrogen peroxide or some such, the simplest Meathod I've seen so far is to safeguard the root system from light. They talk about foil alot. I've got a white 5 gallon bucket so my question is 'is light translucentse like the glow through a white bucket a no-no too?' If the answer is yes, I thought of ways to cover the outside of the bucket(s) with food grade black plastic like, ether on the outside (could use just garbage bags n duct tape.. lol 'lawn and leaf') or on the inside where the food grade stuff might count. Heck, why not both? Love peace and chicken grease!

    Lordhooha Well-Known Member

    White buckets bad at least wrap them in duck tape.

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