Hydro DWC - 1st Grow - PPM issues?

Hola All,

I recently started my first grow that made it past germination & into a DWC (Drain to Waste) hydro set-up. Due to my inexperience, I have a ton of questions but will try and consolidate them & provide a general idea of my set-up. Any advice is very much appreciated (I’m equally exited and anxious about the process :grimacing: :nauseated_face:):

  • Paper towel method for germination. 1 Gold Leaf Fem seed from ILGM

  • Seed placed into rockwool plug (buffered in pH 5 H20 for 2 hours) after tap root emerged

  • Seedling quickly outgrew the rockwool plug, with the taproot emerging from the bottom on day 6 (Day 1 = germination using paper towel method). Rockwool & seed were placed in a humidity dome at high humidity.

  • Placed seedling & rockwool plug into mesh basket of DWC container with clay pellets (washed)

  • Very light nutrient mix prepped in DWC container (8 Gal container) - 25% of the recommended seedling feed schedule on General Hydroponics Micro/Flora/Bloom series (2.5 mL each).

  • Distilled/Tap water used to fill the DWC container - 37 PPM (H20 only)

  • Ambient Day Temp: 75-77 F / Ambient Night Temp: 68-70 F / H20 temp: 68.4 F / Ambient Humidity: 45-60 %

  • Lighting: 18/6 Hour on/off schedule - 150W HPS Sun Systems + 40W LED grow light for added blue light

  • Misc. Info - Exhaust fan running 24/7 through a carbon filter - An additional cooling fan is present inside the grow tent to control ambient temp (HPS light gets very warm and is at it’s highest point of elevation within the tent)

Day 7 (Current):

Major Question at this point:

  • My PPM was at a comfortably low rate after H20 and v. light nutes were added (about 90-110 PPM). Balancing the pH became an issue - In order to maintain a 5-6 pH level within the system (using litmus test paper), pH low (General Hydroponics) was added and raised the PPM to almost 500. I drained and re-filled the system twice with the same result of the pH low drastically raising the PPM to reach the desired pH - is this cause for concern given the young age of this seedling? PPM is currently sitting at 518 with about a 5.5 pH. Should I wait it out and see how the plant responds or drain again and attempt to re-fill to achieve a lower PPM? Is there a better method of lowering pH without jacking up your PPM?

I am planning to add additional nutrient additives on top of the GH Micro/Flora/Bloom once the plant reaches a legitimate Vegetative Stage & Beyond. In no particular order - these are what I have planned based on research from other Hydroponic grows:

Diamond Nectar
Crystal Burst
Snow Storm Ultra

Thanks in advance for any help - this Forum has been wonderful to learn from. I’m hoping I can use it to finally achieve some smokeable results!

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Update: I completely drained the system on Day 8 (Day 2 in Hydro) and replaced with 100% distilled H20 (002 PPM). I was able to readjust the pH to about 5.5 (litmus test paper) with 25% GH recommended seedling nutrition schedule - 128 PPM!

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Here’s a more specific Support Ticket for hyrdoponics. Please be as detailed as possible and if you can get a picture of the roots in white light.

COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

What strain, Seed bank, or bag seed
Age of plant
Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
Vessels: Pots, Grow beds, Buckets, fabric pots
PH and TDSof Water, Solution, runoff (if Applicable)
PPM/TDS or EC of nutrient solution if applicable
method used to measure PH and TDS
Indoor or Outdoor if indoor, size of grow space
Light system LED, MH/HPS/CMH/Fluorescents, or other
Actual wattage draw of lights
Current Light Schedule
Temps; Day, Night
Humidity; Day, Night
Ventilation system; Yes, No, Size
AC, Humidifier, De-humidifier,
Co2; Yes, No
If growing Hydro some additional questions:
DWC? RDWC? Autopots? Ebb and Flow? Other?
Distance of liquid below net pot (DWC)
Temperature of reservoir
TDS of nutrient solution

Always try to upload a clear picture in white light of any issues you may have to allow the community to assist you.

I will tell you that strips and drops are not accurate enough for our uses. You need a decent PH and TDS meter if you are going to do hydro. You might also think about investing in an R/O Buddy.


Thank you! I used a pH meter this time around & you were correct - litmus test strips were way off. I will update the grow with your recommended Support Ticket & pictures of roots once the crop develops a bit.


The plant is so small, are the roots even reaching the water yet?

My thought too are you top feeding/watering it or spraying the bottom?? That little guy might not see the water yet

At that stage, my roots weren’t even sticking out the net pots to feed off the water under so i was top feeding.
What i did learn though, was when top feeding by hand, water around the edges to force the roots to reach for that moisture, and don’t do it too often.
Believe it or not, my roots really took off AFTER i stopped babying them with the top feeding and just forcing them to reach for the moisture in the buckets.

Like @Myfriendis410 suggested, you’re really going to want a good TDS and PH meter and steer away from the test strips.
The PH in your system is going to have some swing to it, when i refresh water with nutes its always 5.8, then swings up, so when it hits around 6.0-6.1, i PH down back to 5.7-5.8.
You might be more susceptible to ph swings than i am due to the smaller water mass in the system.
More water in the system, more stable ph is what i’ve been told.

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The first tap root just popped out from the bottom of the mesh pot. I don’t top feed, but it gets maybe a small spray or two per day of distilled water - back splash from adding moisture to the tent walls.

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I went out and bought a 2nd (higher quality) pH meter and it seems to have made a big difference. The cheaper meter was head and shoulders more accurate than litmus strips, but too variable for my comfort level. I’ve been able to keep the pH relatively stable between 5.4-5.8. I had to readjust recently from 6.1 back down to mid 5’s after adding some hydrogaurd and increasing the feeding to 50% of the GH seedling schedule (178 PPM). I’ve drained the DWC to encourage root growth since noticing the first root coming from the bottom of the mesh pot. Will upload pics soon

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