Question about TDS w/ RO water

[StonerJ]

I'm a newbie to hydro and am in my first grow with it. I plan to change to fresh nutes tonight and am preparing a bucket for the change. When I first fill it with RO water (5 gal), I get a ppm reading of anywhere from 5-8ppm. OK, so far so good. Next, I get a pH reading of 8+ (today's was 8.54) so it's way up there.

Now I'm reluctant to add any nutes to water with a pH that high (to say the least) because I'm concerned about precipitation of the micro-nutrients. OK, so I add some pH down. Even a tiny bit takes it down by 4-5 points! I assume that this is because of lack of buffering of any kind. What blows my mind though is that after adding pH down (using GH, the orange stuff), now my ppm is 150. If I overshoot or undershoot (I just want it down in the 6's before adding any nutes), and add more pH up or down I add just increases the TDS level even more.

Is this normal? Does pH up or down use impact TDS readings that much? I mean my tap water runs about 150ppm so it seems like a waste to be using RO water when I'm already starting out at 150ppm without filtering. Obviously, I'd still need lower pH with tap water and so would be adding on top of the 150ppm but it just seems like I'm negating any advantage i get in terms of keeping TDS levels down to a reasonable level.

Just trying to understand if I'm going about this properly and benefit from someone else's greater knowledge & experience.

I'm thankful for any help I can get with this.

 

[nibec]

nope, not normal.. however, never run your ph meter, in a solution with no/very little ppm... it can damage your probe, and gives you readings that are not correct.

what you should try, is take a gallon of RO, add some nutes to maybe 200 ppm... check the ph, then get it in the proper spot, and then check tds again... you should notice no change..

in a gallon of water, one drop of ph down should change it a lot. for example... if i take a cup of water, check the ph, and its at 6.0 , then add one single drop of ph down, it shoots it to 2.8 ph. with no ppm change.

 

[StonerJ]

nope, not normal.. however, never run your ph meter, in a solution with no/very little ppm... it can damage your probe, and gives you readings that are not correct.

what you should try, is take a gallon of RO, add some nutes to maybe 200 ppm... check the ph, then get it in the proper spot, and then check tds again... you should notice no change..

in a gallon of water, one drop of ph down should change it a lot. for example... if i take a cup of water, check the ph, and its at 6.0 , then add one single drop of ph down, it shoots it to 2.8 ph. with no ppm change.

I did play around a bit with another bucket of RO that I drew. I discarded the first one thinking that I just didn't want to start with ppm that high if using RO water. I just used too much pH down to begin with I'm thinking. Probably reacting to the fact that I've had some buckets of distilled water that needed about 3ml/gal of pH down to get any noticeable effect. I initially put 7ml into the first bucket and the pH dropped like a rock from 8.64 to 3.3. I then added some pH up and by the time I got it back up to a usable pH, I was at 218ppm.

The second bucket, I put 1ml of pH down into 4.5 gals and it brought it down from 8.6 to 3.9 and a ppm of 24. I put about 1ml of pH up in and it came up to 5.2. A few more drops brought it up to 6.01 and only 28ppm so I stopped there.

I'm two weeks into flowering and want to do a flush for 24 hrs before starting back in with a lower level of nutes. I've been using Technaflora BC nutes at their recipe level and have been burning leaf tips slightly and curling the new growth leaves around the buds. I've removed solution & added water for 2 nights in a row until I was at 2/3 of the recipe level and still had dropping pH & climbing ppm when I checked this morning just before lights out. It's in 6.0 water at the moment and tomorrow night I'll add back nutes at 1/2 the recipe level. That should give me about 600-700ppm and I'll see how it looks.

Here's a pic I took last night. I just don't like the looks of those small leaves around the flower and every bud site is like that.

Thanks for your help. Still learning the hydro side of things and I appreciate all of the advice I can get from more experienced hydro growers.

 

[nibec]

1 ml is a lot... in my 5 gal bucket.. and using RO, i add my nutes, and if my ph is at 6.0 i add 20 drops (so about a quarter of a ml) to get it to 5.5 ph.

you should never check the PH of RO water by itself, only after adding nutes. like i said before, checking the ph of something that is so pure, will damage your equipment, and never give you a proper reading...

 

[StonerJ]

Thanks, here I was thinking that 1ml is a tiny amount. Guess I'll need to adjust my thinking into finer increments.

 

[StonerJ]

OK, so I completed the 24 hr flush this evening. I then took a fresh 5 gal bucket of RO water, and added nutes for 2 gals. I ended up with a pH at 5.7 so I added a few drops of pH plus to bring it up to 5.9 and the nutes are at 600 ppm.

Worked out perfectly. Thanks for your advice.

 

[nibec]

no problem buddy. your PH meter was just giving you the run around due to not being able to give you a stable reading, until you had tons of ph buffer in there, raising the ppm to where it would sense something.

 

[HydroManster]

From the way your plants leaves are clawing is usually a sign of to much nutrients, mainly nitrogen.

I would suggest you to lower PPM level in the solution.

They also look a bit over watered, which in hydro usually means there is a problem with the roots some where, possibly lack of oxygen in the water.

 

[StonerJ]

From the way your plants leaves are clawing is usually a sign of to much nutrients, mainly nitrogen.

I would suggest you to lower PPM level in the solution.

They also look a bit over watered, which in hydro usually means there is a problem with the roots some where, possibly lack of oxygen in the water.

Since my original post, I have cut back the nutes significantly. 6 days ago, after another flush, I reintroduced nutes at 600 ppm w/ a bit of extra cal-mag which brought them up to 700 ppm. She was still dropping the pH every day and nutes were standing still. In the past 3 days, she seems to have stabilized. She's drinking about 1/2 gal a day, pH is slowly rising or steady, and nutes are going down by about 40-50 ppm per day. Nutes are currently sitting anywhere from 490-520 ppm. The flowers are developing beautifully but the larger fan leaves are fading, turning yellow, and some are drying up. The leaves directly around the buds are also starting to frost up a bit with crystals. The dark green is gone in virtually all of the leaves except the leaves on the bud stems and around the flowers. The clawing is still there but is not as pronounced. I have also been using about 25 ml of H2O2 in her 5 gal bucket every few days. The roots sit right on top of the airstone which actually bubbles right up through them. BTW, I'm using Technaflora BC nutes (Boost, Bloom, MagiCal, Awesome Blossom, Sugar Daddy, & Thrive Alive B1 red).

Tonight, I plan to move her to a larger reservoir, 10 gal vs the 5 gal she's in now and reintroduce nutes at a somewhat higher level. Shooting for 800 ppm. The flower development is going at full speed at the moment (she's 3 weeks into flowering) and I feel like I need to bump her back up to support that. The res temp is at a steady 68 degrees (I use a chiller), closet temps range from 67 (n) to 79 (d), and RH is 40%.

She was beginning to look this morning like she's starving for more nutes with the green fading away so I'm concerned now about possibly giving her too little nutes.

Trying to keep her all under control and not so concerned about fan leaves and over veg related areas as long as the flower development stays on track and all of the bud areas look good. Here are some pics from last night's check:

 

[HydroManster]

Those plants look way over fed to me. The leaf tip burn is a sign of a lack of cal/mag but it looks to be due from lockout as opposed to under feeding.

You could probably run just plain water to the end at this point and they will still look over fed at harvest.

For most strains, in hydro (water culture) working your way up to about 600PPM in veg cycle is suggested, and the max in flower is about 800PPM by week 6 (flower). After week 6 most strains will not uptake much more nutrients after that time as they have plenty stored up. At week 6 in flower you should just start to taper back down.

It is important to get the plant to use up what it has stored during its life and this translates into a "clean" final product. If you over feed you will NEVER get the plant to use up what it has stored. I think this happens more than we realize and this problem is OFTEN blamed on an additive or the nutrient that made there bud "taste bad". Others will say it was not flushed properly and that is BS as well. No amount of flushing will help a over fed plant during its last days or week before harvest which is when most begin there so called "flush".

Have yet to see a strain that needed more nutrients than this. If you hear growers talking about "pushing" the plants with nutrients, that is just a waste and you will NEVER be able to really flush them properly or cure them properly for that matter. And you will also not gain any yield from over feeding either.

 

[StonerJ]

Thanks, I'll give that a try. I'll move her over to the bigger res tonight and just give her pH adjusted RO water.

 

[HydroManster]

I am not sure that is the best idea either. Are you for sure at week 3 of flower right now?

Try running RO water with about 150PPM of cal/mag for about 24-48 hours, then bring your PPM up to around 500PPM - 600PPM with your bloom formula. See how they respond, if your 3 weeks into flower, you want to try an avoid stalling them. You should see a gradual rise in ph and a steady drop in PPM if they are eating and drinking.

Keep them drinking and eating up until week 6 and then start to taper back down to 150PPM to 200PPM. If your planning for a 8 week flowering cycle then by week 8 you should be back down close to 200PPM - 300PPM.

Double check the root zone carefully and look for any potential problems.

 

[StonerJ]

Positive about week 3. I flipped the lights and changed to bloom nutes on sat 3/17 so she was 3 weeks exactly this past sat 4/7. She's currently day 24 since the flip so she's coming up on 4 weeks this coming sat 4/14.

I am currently seeing a small rise in pH (no adjustment even necessary) and a small drop in nutes over the past 3 days. She just suddenly seemed to stabilize 3 days ago (she was dropping pH a full point daily until then while nutes held steady) so I've just been checking pH, topping off as necessary, but not adjusting pH at all. She was 5.91 last evening and was 5.99 this morning. I started this bucket of solution 6 days ago at 600 ppm using the Technflora bloom recipe but only mixing for 2 gals instead of 5. I then added another 100 ppm of cal-mag the next day to take her up to 700 but she very quickly dropped back to 600 the next day. The past 3 days the ppm has been dropping anywhere from 30-50 ppm per day while pH has been steady or very slowly rising. She measured at 528 ppm this morning.

I have been checking the roots for weeks and there is no slime, the color is good except for some slight "tanning" which I attribute to the Technaflora nutes which I ran as high as 1500 ppm during veg (just following their recipe no less). There is no smell from them and they don't feel slimy at all. When i had the large male plant in the bucket with her and had to remove him, I did have to pull the root mass apart since they were tangled together but it wasn't a problem.

 

[HydroManster]

You might be ok and just stay where your at if you are seeing the rise in ph and drop in PPM. When you see the ph lower and PPM stay the same or rise then you know it is to strong. Your about where you should be now anyhow as far as PPM levels go.

In about a week if everything stays the same, bump it up about 100PPM at a time until you max at around 800 to 1000PPM. If at any time you see the ph drop and EC/PPM stop dropping, stop there. Then after week 6 or 7 start to taper down and make the plant start using up it supplies.

Stay the course and you should get a nice reward.

Cheers!

 

[StonerJ]

Thanks, I'll do the reservoir change tonight and give her fresh nutes at 600 ppm. I do want to get her into a bigger reservoir regardless because the root mass seems huge and I would like the 10 gal instead of 5 gal reservoir to hopefully kind of buffer everything a bit. I'll be away for 4 days at the end of this month (4/27-30) so I'd like to have her as stable as possible. The bigger reservoir has a float valve so I can keep her topped off (gravity feed) and if she's stable in terms of pH I'll be able to let her go for a few days.

What about water level? I do keep the level pretty high, well above the bottom of the net pot Would it help to bring it down & create an air gap?

 

[HydroManster]

Yep, you want to always lower the water level to create a air gap when you get into flowering stages (about a inch gap will do). This does a couple of things, one being it simulates a drought and this causes the plant to grow even faster. The other thing it does is allows for a gas exchange to take place in the root zone.

The bigger res is a great idea as well. The more water you have the more stable you can keep the solution for longer periods of time. The more the plants eat the faster the water solution can become "out of balance", meaning to much of one thing and not enough of another. Since we usually do not have the means to test for EACH element or mineral and its availability (just because it is present in the solution does not mean it is available to the plants), the simplest "fix" to get the balance restored is a drain and refill.

 

[StonerJ]

Thanks for the good info. Going to move her tonight.

 

[YardDog35]

PH up and down WILL increase ppm. Increase is even more drastic if you use both.

I must have missed what type of set up you are using, but sounds like DWC. Yes you want the water level below the bottom of the net pot.

Sounds like you're on the right track! Good luck with the rest of the grow

 

[StonerJ]

Yep, you want to always lower the water level to create a air gap when you get into flowering stages (about a inch gap will do). This does a couple of things, one being it simulates a drought and this causes the plant to grow even faster. The other thing it does is allows for a gas exchange to take place in the root zone.

The bigger res is a great idea as well. The more water you have the more stable you can keep the solution for longer periods of time. The more the plants eat the faster the water solution can become "out of balance", meaning to much of one thing and not enough of another. Since we usually do not have the means to test for EACH element or mineral and its availability (just because it is present in the solution does not mean it is available to the plants), the simplest "fix" to get the balance restored is a drain and refill.

OK, she's all moved. After adding nutes, the pH settled in nicely (RO water) at 5.88 so no adjustment was needed. The ppm was a bit higher than I wanted at 750 but it was also against a base of 20 which was most likely residual old solution from the chiller loop since the RO went into the res at 5. Worst case, if the girl isn't happy I can remove a gal of solution and replace it with fresh RO water to bring the ppm down.

It was a bit of a PITA since I have the chiller pump in the reservoir along with the airstone of course. Not so much fun trying to do everything in the closet! After shutting off the pump I removed the tubing from the pump outflow & thoroughly blew all of the old solution out (through the chiller) into the old bucket, then attached it to the new reservoir's pump outflow nipple. Then I removed the chiller return line from the old bucket and attached it to the return line on the new reservoir. I turned the pump on to get everything going and there is about a 4' gap between the return line and the solution level so the water splashes quite a bit coming in from the chiller return. I also now have two air stones in the new reservoir so there is lots of air, looks like a white water rapids run in the res now. Additionally, I added 50 ml of H2O2 into the new res to hopefully offset any bacterial issues. The root mass has a ton of room in the new res so it's nice not having everything (pump, air stone & root mass) crammed into a 5 gal bucket as before. The mass is huge, almost like a basketball, about 10" in diameter.

So now, I wait & see. I'll continue to check her twice a day, first in the morning just before light out and again in the evening after light on (run the light 8PM-8AM). The morning will give me some kind of indication on how she likes her new home.

 

[nibec]

sounds pretty complicated imo.. makes my setup look like a child put it together just a couple airlines, a hole for adding water/nutes, and a drain

but as long as she works for ya, then its no harm no foul

i was using h202 at one point, but only after i was having root rot issues.. and it never quite did justice on fixing anything.(slowed it down, and held it back, but never cured) so, im going to plug using a benny tea one more time, just incase you run across root rot, maybe it will stick in the back of your mind.. as it is a miracle solution i tell ya. cured it within a week.

broken record, i know, but.. when something works so well... i feel the need! haha.