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Switched from RO to Tap. Seeing some N Toxicity. Not sure why.

So I've been growing for about 15 years anywhere from from 4 light rooms to 100 light warehouses. I have always used RO water with great success. I recently changed over to a salt based mix and so far so good. I had my water tested at one of my grows so i could swap over and use tap water.

Currently i have a 12 light room using RO water with the salt mix in coco in 2 gal smart pots. All of these plants look great 3 weeks into bloom and no signs of N Toxicity. Then i have my other room which is 4in rockwool on slabs. While these plants were in veg I was using the same salt mix with RO water with no problems and put them in my flower room onto slabs and was watering with the same mix and RO water and everything looked great. I flipped the room into 12/12 and started using my tap water with the same mix as my levels of everything wasn't really that high ( see attached water results). About 4 days into flower I started seeing what looked to be nitrogen toxicity. Which was Leaf tips on some leaves clawing down at the tips with some bottom leaves going shiny. So i dialed back my calcium nitrate to dial back my N from (NO3-) 131ppm (NH4) 11ppm = 142 ppm Nitrogen to (NO3-) 115ppm (NH4) 11ppm = 126 ppm Nitrogen. People I know are running their Nitrogen as high as 150 with no adverse effects. When I dialed it back i did see some improvement but it has only been a couple days. Just curious if any experienced growers have any input about this maybe being caused by something in my tap water. Possibly sodium, chloride, or my alkalinity. I also changed my veg over to tap and my moms started showing the same thing. I drained my water tank and started filling with RO water to go back to what I was not having issue with. But I would like to try and figure out what the issue could be.
WaterResults.png


This is the current ppm numbers with my tap water. I'am also adding about 50 ml of PH down with a 0-21.5-0 of phosphoric acid which adds about 25 ppm of P.
New Mix.png


Here is a picture of the plants in veg with RO + Salt mix.
Veg.jpg


The Plants a couple days into bloom
Bloom.jpg
 
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Agree they look fine. I can't think of anything definitive but lots of maybe's.

More light?
Higher temps?
Lower RH?
Lower ph?
Improved nutrient uptake from possible change in micros?

I wouldn't worry about it to much and just adjust feed based on the plants. They look really nice and healthy.
 
Yeah i Guess i didn't really post a good picture. Pretty sure it was a N toxicity. I lowered the N. Also see what looks to be low Mag so I recalculated my mix with some higher mag. My PH also shot up which caused a little PH burn but that's corrected now. I've been using the same mix for the last 15 years so i went through trying to correct stuff 14-15 years ago and dialed in my mix. So I'm just going through that again and its been a long time since I've had to chase def/tox problems. It was just throwing me off because my coco room wasn't showing any signs but then again coco isn't rockwool soo. I guess OG can be finicky with high N.

They're under 6 1k lights but I always slowly dial up to super boost never had and issue
Keep my temps at canopy level at about 78-81 as I am adding Co2 - Everything is charted on my Smart bee
RH is kept at 60-70% right now with my temps to keep early bloom VPD
PH is ran through at 5.8 usually I monitor my run off since I'm in rockwool but ofc I I didn't for a couple days and it bit me in the ass. It shot up to 6.5 doh
Definitely could be better nutrient uptake since all my micros are on point. My old mix didn't really have micros but I'm not sure since a lot of nute bottle don't list everything.

My coco room currently.

20190806_165035 - Copy.jpg


My slight N toxicity. It was effecting random leaves through the room
20190816_171503 - Copy.jpg


Having some drying/burning on my leaf margins
20190816_171554 - Copy.jpg


The result of my ph burn. It hasn't progressed since Ive been adjusting runoff back to 5.8 every night.
20190816_171618 - Copy.jpg


The room currently.
20190816_171638 - Copy.jpg
 
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Yeah with tap you should find a more stable ph but also it will be a bit higher and may take more ph down to bring it in line. Hid lighting? At 81f might be a bit high as the amount IR is decent. Not seeing heat issue but uptake will be high.

Nice to see you using VPD but I suspect your RH is a bit to high. VPD charts online are hit and miss. Buy a cheap IR gun to check leaf temps and shoot for 75-77f anything above may show heat stress. You need to take leaf temps into account to maximize VPD if your not doing so you can get more out of it.

I'm assuming you have a good handle on VPD use this calculator it will fine tune your VPD and make a big difference there is part 1 and 2 but I think you already understand VPD. Leafs temps are a must to take into account.


I'm not a coco guy but I top flush my RDWC to prevent issues with nutrient build up and I think doing so in coco is important but @Enforcer can probably give you better advice. He is a solid coco grower.

Threw ya under the bus yet again @Enforcer
 
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Awesome room! Could be the extra calcium in the tap water is enhancing nitrogen uptake. They do look a little shiny in the first pic but not bad. Also coc has a CEC and rockwool doesnt, so it could also be the coco is holding on to nutrients that the rockwool isnt. Seriously love the industrial look of that room though. Nice work!
 
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From looking at the second water results, which I’m assuming is the tap water you’re working with, it looks like the total ppm is too high. The ppm of the tap water must be included in the calculation of total strength when mixing nutes. I usually recommend people use RO if their water is over 200ppm total. You appear to be over that in a K alone. You’ve probably already come to this conclusion, but you’ll need to go back to RO or reduce the Jacks formula enough to take into account the total ppm of your tap water.
 
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Unless that second result sheet was after mixing nutes. If that’s the case your water results look ok for that sample. I say “that sample” because water testing results can fluctuate throughout the year depending on weather, source water changes, and level of treatment. With an operation like yours I don’t think I would want that kind of uncertainty. I vote just stick with RO.
 
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Have you tried upping the iron by 1-2 PPM? Mag drive pumps and Iron being immobile. Why I'm at 2 PPM now.

I'm pretty close to what you are running in Hugo's. I'm also on Tap and it is very close to yours. Also remember the 20-30 ppm of P from PH down. Na is always a gamble in tap. Mine averages about 18-20 ppm. My Cl though is low around 4-6 ppm. That is where feed times will have to be spot on vs RO and issues will pop up. Even then if it fluctuates in the base water (prob does) that can cause issues. How stable is your PH in the Rez or are you dosing? Mine is set and forget for 7 days and doesnt move. If using rez's and it's not staying stable that's a warning sign if your aren't recircing.

Untitled.png


What kind of watering schedule are you running? A cheat with rockwool is you can use a syringe about 30 min - 1 hr after the last feed and pull solution out of the slab and test it. PH will tell you if you are where you need to be with the feeds. Just do it after the last feed vs testing the runoff.
 
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Me personally I never really liked stacking rockwool and always had issues like that when doing it. Why i like to use 6in or even 8in (if i was growing bigger plants) vs slabs. Just way easier to control and not dealing with dry spots ect.
 
Only time I get leafs like in the second pic from the bottom is when I do a water change (DWC) and my PH goes tits up.
That's what happened to me. The PH shot way up and I had just sprayed with some optic and Ca25. Came in the next day with some burning but I know it wasn't from the spray as i sprayed my coco room with the exact same spray the same night and had no burning in that room. Since I've been running to 5.8 run off i haven't seen any other burning so I guess that's good.

Unless that second result sheet was after mixing nutes. If that’s the case your water results look ok for that sample. I say “that sample” because water testing results can fluctuate throughout the year depending on weather, source water changes, and level of treatment. With an operation like yours I don’t think I would want that kind of uncertainty. I vote just stick with RO.
The second result is what im adding. I'm in LA and the water ppm hasn't really changed in the 5 years I've been at this place. The room started looking alot better when i dropped N down and started adding alittle more Mag. I went back to the Tap water to get the extra Ca ppm's while also dropping down the CalNit. Almost wondering if maybe I should drop down K alittle bit too. Just trying to make small adjustments as I don't like to make to many and then not be able to pin point whats going on if something crazy happens.


Have you tried upping the iron by 1-2 PPM? Mag drive pumps and Iron being immobile. Why I'm at 2 PPM now.

I'm pretty close to what you are running in Hugo's. I'm also on Tap and it is very close to yours. Also remember the 20-30 ppm of P from PH down. Na is always a gamble in tap. Mine averages about 18-20 ppm. My Cl though is low around 4-6 ppm. That is where feed times will have to be spot on vs RO and issues will pop up. Even then if it fluctuates in the base water (prob does) that can cause issues. How stable is your PH in the Rez or are you dosing? Mine is set and forget for 7 days and doesnt move. If using rez's and it's not staying stable that's a warning sign if your aren't recircing.
So I used to do a recirculating system this will be my second run on DTW. When I was doing recirc I would normally just water once a day in the beginning and about week 3 I would go in twice a day and water to a 5.8 run off. I had great success doing it this way usually averaging around 2.5 per 1k even up to 3.2 per 1k a couple times. Right now I am watering once a day about and hour after lights on and usually until I hit 5.8 run off. I did this on the first DTW run and got 2.5 per 1k but now with salts it is definitely alittle different and thinking I should probably be watering more frequently with shorter watering's. It's just a foreign concept to me because I've been watering the way I am for so long now and it was the way I was taught. It would also require a bit of a watering redesign for me which isn't a big deal I just haven't done the research to figure out the best way to do it.

Never thought of the syringe thing that sounds like a great idea. Mind explaining how you feel I could improve on the watering schedule? Much appreciated

Me personally I never really liked stacking rockwool and always had issues like that when doing it. Why i like to use 6in or even 8in (if i was growing bigger plants) vs slabs. Just way easier to control and not dealing with dry spots ect.
I've only ever use slabs because of how I water it always gave me wiggle room so things wouldn't dry out so fast. I've always had good success minus a few times when I delt with some root rot issues. Your room looks great. Nice and healthy


I will snap another picture tonight when the lights kick on.
 
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The above plants in the pics are on 3 - 1 min waterings atm (17 plants - 1/4 single drip line - 1/2 in pvc - 730 gph bottom draw eco pump - 3/4 hose from pump to 3/4 fitting). Anything more then 3 - 6 sites I dont have the pressure for equal waterings. I hand water veg (once a day at that stage) and they go to 3 the first 2-3 weeks when they go to drip from day 1. After that it goes to 4 and then sometimes 5 depending on the plant. I've used rockwool enough to kind of know when to bump it up.

I don't think I have ever paid attention to runoff honestly but also don't use slabs. I know slabs have to have the drainage holes in the right spot offset from the plants. Try the syringe method. If you ph isn't where your feed is at or maybe .1 above after the last watering you need to water more. That will give you a more accurate reading on whats going on then runoff and what is happening in the root zone. Try from different places on the slab to make sure its uniform.

Plants that size on slabs/4in I def had to water more. That was just my setup tho.

Also make sure you are mixing your salts right. I know you have been at this for a while but not sure how long you have been on salts.

SI first -> PH Down (since SI spikes ph to 10) ---> Nitrates ---> Micros (EDTA - if separate) -----> Sulfates/MPK -----> Mono Ammonium Phosphate (if used always has to be separate and last)

I usually give them 1 to 5 mins between the ----> depending on the substance and how much you are mixing

Anytime man. I'm still brain storming sure I will think of something else in a little.


Is your PH staying rock solid in the Rez for multi days? BTW nice setup
 
Have you tried upping the iron by 1-2 PPM? Mag drive pumps and Iron being immobile. Why I'm at 2 PPM now.
Doing some reading about iron and seeing it can effect Ca and Mag thinking maybe i should bump it up that 1-2 ppm. I supplement with jacks most so ill probably add some that way. And see if it helps. If i just wanted to add iron without using most which iron supplement would be best? Iron edta? Im not at a computer ill have to do some research this evening. I post some pictures i snapped lastnight too this evening.
 
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Doing some reading about iron and seeing it can effect Ca and Mag thinking maybe i should bump it up that 1-2 ppm. I supplement with jacks most so ill probably add some that way. And see if it helps. If i just wanted to add iron without using most which iron supplement would be best? Iron edta? Im not at a computer ill have to do some research this evening. I post some pictures i snapped lastnight too this evening.

Yeah that would be the easiest. Also something like Peters S.T.E.M which is all the micros.


4lbs for 20 bucks will last you a long while

The iron chelate I have is Sprint 330 and its Iron DTPA not EDTA 10% iron. 0.1g a gal gives you like 2.5 ppm of iron.
 
This is a good read on it
Some good info in there! Thank you for that. So i started adding my PH down after my K-Silicate to get my ph down to 5.8 before i started adding in my other nutes so the micros getting added in are safe. Also to your other post I add jacks M.O.S.T which is trace elements to boost up trace nutes as i need them. Pretty sure the pump I'm using isn't a mag drive pump

K number seems a little high for coco coir.
I think you may be right i started seeing some yellowing in my coco room. i dropped my K down to 160 and things started looking better so thank you for that.

I changed both rooms over to the lower K mix and have just been flushing through to a 5.8 run off and things are exploding. I had some thinning of top leaves that would seem to say too high of a K value so that was the reason for the change.

Just wanted to say thank you to everyone for the input. It helps to have conversation about things I may be ignorant to or things I've lost over the years. It's always scary to change over from something that's been working for years but I think that's what keeps this fun. So thank you.

Here's some update photos.

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20190819_211412 - Copy.jpg


The coco room a couple days ago. Day 25 out of 60

20190823_184708 - Copy.jpg
 
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Good to hear. We are all always learning and threads like this always help for reference for the future.
 

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