Nutrient lockup/Salts the problem in my hydro setup?

My grow is about 5 weeks from germination.
I am new to the site and dont know where to fill out the ticket info I keep reading about so I will give a breakdown of what I do know.

Strain: WW Fem Purchased from ILGM
System: DWC in 5 gal drip ring system.
Medium: Hydroton rinsed well prior to grow
PH: 5.8 - 6 in all 9 buckets
PPM (with nutrients) 800-900 ppm
Nutrients used: Foxfarm GrowBig and Foxfarm Bloom used together as per instructions.
Light cycle: 18/6 VEG
Lights: 2 - 1000W HPS
co2: approx 1100 ppm (on auto ppm metered regulator)
Temp: High @ 81 F and lowest at 62 when light is off
Room dimension approx 10’L x8’W x7’H
RH: between 35% & 45%

I began noticing that the leaves and the plants as a whole began looking droopy and the growth seemed to be quite slower than previous grows. I have began topping for more top colas which has worked well and I also have pruned a little on the bottom 1/3 of the plants. Noticing things getting worse in the last week, 2 days ago I decided to flush the systems and replace the solution in the resevoirs with ph’d and tepid water. The water used was ph’d to 5.8 and has a ppm of 180 straight from the tap. My questions are:

Is this nutrient lock-up due to salts?
Should I be flushing with straight ph’d water?
If so, how long?

Any other insight to my issues even if it appears off topic would be greatly appreciated.
Thank you, Hydro Red

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Looking at your pictures and the parameters in your room, I’m really leaning towards the temperatures as being a significant part of the problem, not only is there a huge variance between day and night temps that could potentially cause problems even if you were growing in soil, the temperatures for DWC hydro should never be much below 65F/18C and never above 78F/25C, so if you air temps are 62F-81F (high temps may be even more important as above these temps the dissolved oxygen in the water drops very low and you could have problems like pythium and other problems similar to “over watering”) – your reservoir temps will be about the same as you air temps, maybe a degree lower, but that would still be far outside the healthy ranges.

You can try more aeration, this can allow you to get nearer the higher temps and keep your plant healthy, but you likely need to look into better venting of heat build up during the day and a heater for overnight.

The droops in a DWC system are usually attributed to lack of Oxygen in the res’

I was also concerned with using 2 different nutrients together. This can cause issues if you are not careful in making sure you are not feeding the plants the same minerals twice.

As of this far in, I have no bubblers in any of the res so your replies both coincide with my situation regarding oxygen to the roots. I will get some bubblers in each of the buckets and hope they wake up a bit. I am also going to build a wall tomorrow to seperate my grow area from the rest of the open space and then I figure I should be able to get my temps in check quite easily once this is done since there will be an actual evacuation of the heated air when the lights are on… Thank you MacGyver Stoner and latewood for the quick replies, and I will get back with results here in a day or two. -HR

The air pump is not providing aeration to the buckets? Or it does but you are adding fine bubble aeration stones?

Finer bubbles will help, more bubbles will help. Possibly putting the buckets on the bare concrete floor might help as it might be kind of cold and act to kind of suck heat out of the buckets.

Good luck and we look forward to seeing your room develop.

Well, I have the 10 outlet commercial pump (105W 85Lph)supplying the bucket drip systems. I dont have anything for oxygenating the res. I did however get it set up to have bubbler stones in each of the buckets individually and I have ordered another pump that should be here in the next few days or so. Until then I have the bubblers and the drip rings all connected to the one pump for now. The drip rings still work wonderfully, but the bubblers in each of the buckets are hardly bubbling enough to really do too much though I’m sure it is better than nothing for the time being until my other pump arrives. I have also managed to get my temps under control by reconfiguring my room and placing fans/heaters in different various spots. I have been monitoring it since I was advised about the temps (approx 10 Hrs) and I believe it is under control now. My lowest temp so far with the lights on is 73.6 F and my highest temp is 78.9 F. If I can manage these temps when the lights are off I believe I will be golden! I started to add another heater but found that just by moving some things around and changing my venting from the light, and moving my circulating fan, that I am managing much better temps with ease. Fingers crossed that the girls perk up soon because they are looking sad and tired. I also wanted to add that I have put nutrients back into the systems and have a reading of a very light 360 ppm until I get things in check. I feel this should be a safe/low enough number where the plants can still feed, but I dont think I have to worry about over fertilizing. Less is more as I’ve read.
Just an fyi- my water temps in my buckets have never gone below 68F or above 74 since day 1 so I dont believe water temps to be suspect at the moment…but we shall see. Thanks again, -Cheers

Yes, if you can keep water temps below 75F and above 65F you should do much better. Very very low PPMs might have a hard time keeping the pH stable, just an FYI, at about 500-600PPM you will get better stability and shouldn’t have to worry about nutrient burn at all.

Well, it was obvious the following afternoon that my last attempt at temperature controll was a failure so I revamped the room and put up a wall to close off the grow room and also to make a seperate room to draw my cool air from. A new thermostatic fan controller with the hot air ducted out of the room and some other fixes like a night time heater, I have managed to keep my room between 68F when the lights are off for 6 hrs, and 77F when the lights are on for 18 hrs. I’ve got about 2 days of this consistantly and the girls are already on their way to recovery. There is lots of new growth and they are climbing again-which is something they havent done in about 7 days. I still think I can dial my temps in maybe 1-2*F closer together with a bit more time. Thanks for the help and tips. I’ll be sure to put some pics up once they fully recover and look a bit prettier :oops:

I have to add. I believe the optimal DWC temp is 60-70 degrees f. The cooler the water the smaller and more efficient Oxygen molecules occur

Yes, around or a bit lower than 70F is a real good place for the reservoir temps to be in DWC. I’ve read much below 65F is not necessarily making things much better and obviously if you get much below 60F you can start getting root problems.

Well it is not really about the smaller and more efficient Oxygen molecules with colder temps, that is not exactly how it works. It is more about the size and shape of the water molecule. It has some to do with the same reason water is one of the few things that expands as it gets colder/freezes whereas most everything else shrinks as it gets colder/freezes. Dissolved oxygen is absorbed into water better at a moderate temperature, much above 70F and the ability of the water to hold oxygen molecules between the water molecules is greatly reduced.

Hello, I just wanted to give an update on my room ( 8 days from last picture)and my problem was most definately temps. I have it all worked out now and got a wall up to seperate the grow room and gain control of the environment. I have it at a beautiful high of 74F when the lights are on, and a pleasant low of 66F when the lights go out. My humidity hangs around 40%-50% on average here with the midwest temps being -15*F.
I have gained considerable growth since the last photo as well and will most likely be going into flower within the next week or so. I have been steadily raising my nutes ppm every top off of the reservoirs. Im running 5.7-6.0 on my ph and 480 ppm at the moment (Foxfarm big grow Veg 8-4-4), but they are drinking a lot of water now so I will be bumping that up in faster increments and will be closer to 700-800 by the time I flower and begin adding P-K Bloom nutes.

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Well you appear to be much happier. :slight_smile:

Another update. Less than 2 weeks into flower. Made and added the scrog net (under $18 U.S.)

Im using the same buckets, my bucket top is black too… Mine a top feed DWC too. I have 400W bulbs and if they get closer than 36" to the top of the buckets the plants suffer, i think the lights heat up the buckets too much when theyre too close, even with an air stone in each bucket.