Questions regarding pH management with hard water

Ok, to start off I am a rookie coco grower with one run in so far. It seems to me that pH is the key to a successful grow and my pH issues just never seem to stabilize ever. It starts great, then no matter what, it just goes to shit.

The first plant I ran looked great until week 4 or 5 of flowering, then it started yellowing as if it had N deficiency. I tested the runoff and noticed it was salt building up so I flushed with half strength until my ppms were in the range I wanted. To fix this issue I run a feed, feed, water schedule. This keeps the excess salts from building up.

I believe my nute issue is solved, but now this grow I seem to have a pH problem. About 5 days ago my plants in week 5 of flower started yellowing/ tip burning and those leaves eventually turn darker brown and shrivel off. I've been watering with approx. 1250uS/cm (~800ppm) at 5.8pH the whole flower cycle so far with a regular flush on the weekend, and now all of a sudden when I tested my runoff to find the problem, I read 6.5 on a majority of the older plants. WTF!

Old flower nute solution:
1.5 tsp. PBP Bloom soil
1 tsp. Liquid Karma
1 tsp. Unsulphured Molasses
1 gallon 7.8pH tap water
pH down to 5.8

This solution gave me 850-900ppm

This is what I gave them up until now with a 30% runoff each watering. I am now adjusting pH to 5.0-5.2 before feeding because when I feed at 5.8, the coco just stays at 6.2 and will eventually raise like I am seeing now. I managed to get the pH of the troubled plants back down to 6.2, but breaking passed that barrier is hard to do. I will try another 5.0 flush tonight. I also cut the molasses out of the feeding and am going to use 1 tsp. of CalMag+ instead. Perhaps my cation exchange is out of whack, although most people say not to use CalMag after a couple weeks in flower. I figured since my water is kind of hard, I didn't need it either. If the Cal-Mag doesn't help my problem, I won't continue using it.

Since I have to know how everything works and this problem is really annoying me, I won't stop until I figure out what I am doing wrong. It doesn't matter how much you read about something, things still fuck up and you have to correct them, this happens to be one of those times. I am about to get an RO filter for my water supply just to rule that out of the equation. The plants look so good in veg and through stretch, but then I screw something up and they turn to shit with a high pH.

I took one of the plants with a 6.5pH runoff and put it into a larger container so I could flood it. I poured my 5.0pH, 800ppm solution through the pot until it was totally submerged. After 10-15 minutes I took the plant pot out and measured the pH of the solution in the larger container and it read 6.1. However when I ran more water through the plant's pot and tested that, it was at 6.3. So I do believe coco buffers itself to a certain pH and breaking that buffer is a bitch. I did the soaking for three cycles and it finally measured 6.1. After this I stopped flushing. I am going to try again tonight to get it below 6, but am I screwed now? Should I just say fuck it and let them go the last few weeks with a pH over 6?

New flower nute solution:
2 tsp. PBP Bloom soil
1 tsp. PBP Grow
1 tsp. Liquid Karma
1 tsp. Cal Mag+
1 gallon 7.8pH tap
pH down to 5.3

This mix gives me 1100-1150 ppm


Sorry for the long post, I just tried to cover every detail. Here is a picture from the 3rd, 8 days ago. This is about when the yellowing was starting to get bad. The older plants are the middle and left side. The runoff wasn't measuring terribly high though, around 6.2pH at 900ppm. Then this weekend when the problem wasn't getting better, I measured again and it was 6.5. The younger plants started showing the very early signs, but I corected pH and now added some Cal-Mag to hopefully help. Something happened and I'm not sure what caused this. I will grab a recent pic tonight when the lights come on, but most of the fan leaves are gone now. The buds are still green and seem to be growing, albeit slowly. Any help or words of wisdom would be mucho appreciado! I don't want to go back to soil but coco is kicking my ass.

Edited by TBM, 12 June 2011 - 05:18 PM.

What type of cal mg are you using? If its not chelated build-up can cause ph problems (you probablly already know this though). I would deffinitley get an RO filter asap. I dont know how good your tap water is, but coco is somewhat organic hydro. I deffinitley wouldnt want to use tap with an e&f!

Botanicare Cal Mag+. I cut the cal mag when I start flower(although I recently started adding it to the flower mix), so build up from that wasn't an issue leading up to this problem. I keep my EC and pH monitored also until I learn more about coco. The EC stays consistent with a 30% runoff, but the pH went up to 6.5 so something is out of whack. I lowered the pH through lots of soakings with 5.0pH water. I added cal mag to make sure I wasn't getting lock out also due to the nature of coco being a hog on Ca and Mg. Taking the water out of the equation by purchasing an RO filter would be my next step I think.

The tap water is the only thing I can think of that could be causing the imbalance. It just seems like nothing stays stable even though my feedings and runoff EC are. Maybe they just need a lot more food and the yellowing is just lack of N, I don't know. My waterings and feedings were always consistent. I bumped from 800-900ppm to 1100-1200ppm. If they don't pick up, there must be an imbalance somewhere.

I may have tried to correct too much already, but I'm hoping I find the answer before it spreads any more.

Edited by TBM, 12 June 2011 - 03:38 PM.

From the looks of it, i dont think your babies have n deficiencies. They seem pretty green and delicious considering how far along they are. I have had the same problem with ph, except mine was too low. My leaves curled up, instead of down. 7.8ph is pretty high, did you add anything to the tap to make it that high? Because god only knows what the city adds to drinking water to make it "safe."

Nope, I don't add anything to it, I just let it sit a day before using. I just grabbed a jug I had sitting to evaporate the chlorine crap they put in and tested it. 7.7pH at 200ppm. Not sure what the hell is in this water, but I have to use more pH down than I'd like to. It sits at 6.8 after adding nutes so I add probably close to 1 tsp. of GH pH down. Are there ill effects from having to adjust the pH this far? I've never had to be concerned about pH until now, so I'm still a newbie on most of the particulars.

Thanks for reassuring me about the N deficiency. Since I lowered the nutes to 800ppm when this problem cropped up, the thought crossed my mind. I have to assume its my water that they don't like. This happened the last couple grows now and always happens in week 4 or 5. I have a perpetual system and the younger plants on the right just started showing slight yellowing. I hope the CalMag fixes it becuase I did not use any when I started flowering. I also noticed dark purple on the stems, which some attribute to lack of Mg or P.

Usually growers see Ca or Mg problems at this stage, but mine don't look to show those symptoms, so I have to assume it is the pH of my source tap water or a cation imbalance. Since it is so alkaline, I was hoping an RO filter would lower the pH at least to 7. 7.8 is way to high, my last apartment only 20 miles away was out of the faucet at around 7. Not sure why this stuff is so high.

Edited by TBM, 12 June 2011 - 05:21 PM.

As long as your ppm isnt out of whack i dont think there is anything wrong with adjusting things too far. I accidentially made my resivour 8.0 by adding too much up, so i had to lower it back to 6.5. I didnt experience any problems. I have always used an r.o because i live in the rust belt. Even though the great lakes are right there, my city is so poor they cant afford to fix water lines untill they break. And all the pipes are from like the 50s. So many heavy metals and oxidized crap builds up in the pipes its discusting.

Also, what type of coco did you use? Most brands of coco claim they "flushed" the coco of their natural salts, making it ph neutral and whatever. But yep you guessed it, they dont flush shit. The abnormalities in your plants could be a result of the salts in the coco, if you didnt flush first, that is.

As long as your ppm isnt out of whack i dont think there is anything wrong with adjusting things too far. I accidentially made my resivour 8.0 by adding too much up, so i had to lower it back to 6.5. I didnt experience any problems. I have always used an r.o because i live in the rust belt. Even though the great lakes are right there, my city is so poor they cant afford to fix water lines untill they break. And all the pipes are from like the 50s. So many heavy metals and oxidized crap builds up in the pipes its discusting.

Also, what type of coco did you use? Most brands of coco claim they "flushed" the coco of their natural salts, making it ph neutral and whatever. But yep you guessed it, they dont flush shit. The abnormalities in your plants could be a result of the salts in the coco, if you didnt flush first, that is.

This coco is Botanicare ready grow and reads 50ppm and 6.2pH out of the bag. I tested by letting it sit in a bath of 5.8 pHed water for half an hour. I went with all Botanicare products for my 1st run in coco. I use PBP Grow, PBP Bloom (soil version), Liquid Karma, and Cal-Mag+.

Now that I think about it, I have a plant in veg the same age as some of the plants showing this yellowing. It looks dark green and lush as can be. I've been feeding this plant with the Cal-Mag+ and PBP Grow only though, thats literally the only difference. 800-900 ppm at 5.8pH makes this plant happy in veg. After a few weeks in flower with my old flower mix they went to hell. Now I think I'm pretty convinced I was using a bad feeding mix by taking out the Cal-Mag. At least I hope.

So maybe it was good of me to switch up my flower mix to incorporate the Cal-Mag. I also swapped 1 tsp. of Bloom for 1 tsp. of Grow. If I knew how to read and calculate nute ratios, I would do the math, but I lack experience in this area, so I guess. Hopefully I am just seeing a weird lockout due to not enough Ca or Mg. Maybe my water has very little, I don't know. If I just went RO my water could be ruled out.

Thanks for the posts, it really helped me sort some things out. I will post my results as the days go by in case someone else has a similar situation as me.

Edited by TBM, 12 June 2011 - 05:15 PM.

Any time bro

hey TBM, I have been gardening with coco for a year or two so i know the horrors and wonders it may bequeath. I am glad you are using a PH meter, it is often useful to have more control over your plants health. I have used the cal mag, i think there are different points of view about how to utilize it however I would say use a little all the time. i have noticed it goes through the root system pretty fast but some is absorbed. using soluble humic and fulvic substances might be good with the cal mag as well.

I think your PH issue can be assessed based on what you are observing of your plants, in addition to the run off. i have not ever been a patient run off tester so i cant say much about that.. If you want a boost to help you another three weeks before harvest make some basic guano tea, (add vermi-T and some fine guano such as sunleaves jamaican, budswel, or guanokalong, maybe some kelp and molasses, to a few gallons of water) or other organic nutrients to help buffer your water, adjust to 5.8 and water in

are your plants in straight coco and perlite? any other amendments? I'll recommend using moderate amounts of organic amendments, such as compost, alfalfa meal, or kelp meal. a little bit of agricultural lime or glacial rock dust never hurt any one either.

Thanks Forbins, I am using straight coco with nothing else right now. I might play around with more organics in the future, but for right now I am just figuring out how this hydro-based feeding system works. I believe I narrowed my problem down to me just not doing my homework and following recommendations that didn't fit my grow. I didn't want to over-do the nutes, so I gave them way less than the label recommended, but I also wasn't giving them enough food either. Or at least the right ratio of elements. The mix I was giving them had way more K than anything else. The N-P-K-Mg of the old mix was 32-55-133-27. That is kind of embarrassing now that I know how to calculate my nute mix. I finally found a chemical analysis of my water which is fine, just a bit high on the pH. My new nute mix brings the pH down to 6.1-6.2 though so I don't have to add much pH down.

My new mix is 109-79-208-53. After taking some time to figure out how to calculate my nute ratios, I was way off the mark. No wonder they were getting so yellow. The tip burn was making me question the lack of N, but all other symptoms pointed toward it. I am sure the pH got out of balance because my nute mix was so weak and that led to the tip burn. I soaked all of the older plants in 5.0 pH water for an hour. The water in the tub after that measured 5.9 pH. Then I started the new nute mix. After a couple days of feeding them the new mix, the younger ones that were starting to pale and twist are looking to be more normal now. Maybe in a few more days they will be fine again. The older plants have been hit bad and lost most of the fan leaves with the remaining ones very yellow, but the buds are still green.

Edited by TBM, 14 June 2011 - 01:08 PM.

I am glad you have got the PH dialed in, thats rockin. I am not sure if the yellowing you are seeing is a nitrogen deficiency, you definitely need more phosphorous than nitrogen during early- mid- late flower, although some might say other wise. so... the yellowing could have been the N deficient, the PH out of wack, or it could be a sulpher deficiency, as sulpher contributes to lush color of leaves. I'll recommend trying to add some epsom salt (i tsp. per gallon) to correct that. Yah coco has benefits but it is not necessary to use it as a stand-alone medium to gain them. adding some earth worm castings, or other organic amendments, gives a steady release of nutrients synthetics may not, as well as increasing the plant's resiliency, perhaps even how well it handles nutrient deficiencies, ph issues, etc. there are some beneficieal micro organisms in compost that assist your roots as well. if you have more than a few weeks before harvest i would recommend a top- dressing of earthworm castings, i dont think youll be disappointed. a 1.5 cubic foot bag usually costs around $20. examine the castings under a bright light before you apply to ensure there are no gnats or mites visible (if yes return and try another brand

Yeah, I just screwed a lot of things up with these first couple sets of clones.

I have nute issues, root-bound issues, and didn't know what veg time I needed on cuttings to get me to the height I want when they finish. Most out-grew the containers I am using. I read people say its fine to let them get root-bound, but to a point. Letting them get too root-bound will lead to issues as well. It is probably attributing to some of the things I am seeing as well.

Growing pains of a new system. I will get it soon enough though.

Yeah, I just screwed a lot of things up with these first couple sets of clones.

I have nute issues, root-bound issues, and didn't know what veg time I needed on cuttings to get me to the height I want when they finish. Most out-grew the containers I am using. I read people say its fine to let them get root-bound, but to a point. Letting them get too root-bound will lead to issues as well. It is probably attributing to some of the things I am seeing as well.

Growing pains of a new system. I will get it soon enough though.

Your plants being root bound is not an issue, as long as the plant's size is proportionate to the container. In general i think you should prune them back, when they are about twice as tall as the container. this will insure there is not too much foliage demanding nutrients and water from an insufficient root ball. BTW I'd say if you have got your cuttings rooted, you've done great, if you are worried about your plants getting too tall practice topping, you can do this as many times as you need and if you're careful, topping the teeney upper buds during the first three weeks of flower will cause the top bud to split into three or four while keeping your plant from gaining height without stressing it too much.

i just posted this in another thread and figured it would help you here.

i have used every combo possible of amendments, organic additions (like your molasses), funghi and bacteria, and everything else you can imagine to make my babies grow perfectly.

in all of this i realized one major thing....

ahkams razor - the most simple solution is most often the best.

hey guys, i havent posted in a while, but i am always reading.....

this thread seems to need little more input for some.....

you guys are really worrying about the ph levels. when in reality you do not need to....if you feed it right.

fortunately or unfortunately, i am unsure of which, i have run into many ph problems in the last year....but i have learned a lot....

i had first started off in soil, and didnt have a proper ph tester. slowly my ph rose due to my hard water here in athens. just as i was ready to put my first girl into flower, she suddenly crashed and died. only then did i buy a ph tester and realize what had happened.

i then moved on to coco, mostly due to Ed and his AskEd coco guide. the coco i purchased online, like yours, had a high starting ph. even though i ran 100's of gallons of water through it, it slowly crept back up to the 6.8 range.

this caused 3 new sets of babies to die.

i had to find a better solution.....and it was much easier than i thought. today i no longer bother with the ph tester as it has become irrelevant.

what i did was purchase a specially designed coco fert for hard water. it includes ph balancers to make things easy. of course i always use a couple drops of superthrive in every mix i make.

the brand i use is vitalink coir for hard water, but i dont think it matters what brand you use as long as it is designed for the medium you are using and includes ph balancing chemicals. the cost for my 1 liter bottle was 11 euros (about $14) and i only use 5-7 ML per liter....so this one bottle (for veg) will last me just about forever. the flower fert is the same price and dosage is the same. this brand just happened to be available here in greece....i am sure there are many more in the states...

so in short, for many months i would have stalled growth until death and always due to poor ph, always trying to adjust it exactly. now i dont even bother to check it. my girls are healthy and vibrant and growing wonderfully.

i should note that due to the high starting ph, before it was time to use the nute formula, it took a little longer than it should to get to the point to use the nutes as growth was a little slow.

remember that if you use tap water, make sure you let it sit out at least overnight uncovered to let chlorine evaporate. also tap water has the necessary calcium and magnesium that coco lacks, so i stopped using the distilled water many months ago.

good luck guys and gals!

oh yeah, and according to Ed, and from my own personal experience, try using a 75% coco 25% perlite mix

i have also added to my newest girls a wick system....a very simple one...

since i use standard plastic pots with trays, i have drilled out extra holes in the bottom (as well as the rim for tying points) and ran a length of hemp string through the pot and sticking out the bottom about an inch or so. the top of the string reaches the top of the coco in the pot.

i no longer feed top down so as not to compress the coco too much. it also makes it easy if i want to go away for awhile as i just put a small plastic reservoir under the pot instead of the tray, with the strings in the water....check out some of the DIY wicking systems in the DIY forum.

this works great!

Thought I would post an update since its been about a week now. My issue was not enough food, mainly N, and the stretch phase used it all. The problem isn't spreading anymore and the young plants are looking good. Best looking buds yet. The new AK-48s now have golf ball sized buds rather than small cotton ball sized buds at this stage in flower.

I guess I just needed to figure out how to calculate my nute ratios and feed the plants properly. I haven't monitored the runoff since the problem started and just fed them at the Lucas formula ratios I calculated. Looking so much better. Even the plants I just threw in flower are showing more bud sites than the previous two rounds. They are about done with the stretch and no signs of the yellowing/brown tips. I might take pics tonight, depends how long I work today.

Your plants being root bound is not an issue, as long as the plant's size is proportionate to the container. In general i think you should prune them back, when they are about twice as tall as the container. this will insure there is not too much foliage demanding nutrients and water from an insufficient root ball. BTW I'd say if you have got your cuttings rooted, you've done great, if you are worried about your plants getting too tall practice topping, you can do this as many times as you need and if you're careful, topping the teeney upper buds during the first three weeks of flower will cause the top bud to split into three or four while keeping your plant from gaining height without stressing it too much.

Yeah, I might have to do this. These two strains love to stretch up 3x their size. I flowered this last set as soon as they showed some growth after rooting and they are just a bit too tall still. Topping is my next option. Thanks for the tips.

This thread is actually super helpful. I am so enthralled with the Ph that if I saw any def. in flowering I know for a fact I would automatically think Ph. I hand water over the top, so I think once flowering kicks in I will kick up the strength of my nutes. It really only makes sense with cocoa (and strain depended) since it retains so much.
I dont know if what i wrote makes any sense. Too blazed. But still super helpful.

This thread is actually super helpful. I am so enthralled with the Ph that if I saw any def. in flowering I know for a fact I would automatically think Ph. I hand water over the top, so I think once flowering kicks in I will kick up the strength of my nutes. It really only makes sense with cocoa (and strain depended) since it retains so much.
I dont know if what i wrote makes any sense. Too blazed. But still super helpful.

Yeah, I got bent up about the pH and runoff too much. Now, I haven't monitored it in over a week. I just give them my new feed mix every day with some runoff. No more yellowing fan leaves or crappy looking buds. The 6 week plants' buds are twice the size as the 8 week ones, so I think I am on the right track now. The youngest flowering plants at 2 weeks also show more vigorous growth and way more bud sites. Its hard to believe I was under-feeding, but I'm used to hot soil mixes where you don't feed much. Now that I think I have my nutes figured out, the rest should fall into place.

Do yourself a favor and get used to using the nute calculator at Cannastats to ensure proper ratios. I must have been getting some kind of lock out also as well as lack of N, so my nute mix was way off before when I just guessed. I now go by the Lucas formula and came up with a close enough mix with Botanicare brand nutes. I'm happy now and so are the plants, so far anyway.

Yeah, I got bent up about the pH and runoff too much. Now, I haven't monitored it in over a week. I just give them my new feed mix every day with some runoff. No more yellowing fan leaves or crappy looking buds. The 6 week plants' buds are twice the size as the 8 week ones, so I think I am on the right track now. The youngest flowering plants at 2 weeks also show more vigorous growth and way more bud sites. Its hard to believe I was under-feeding, but I'm used to hot soil mixes where you don't feed much. Now that I think I have my nutes figured out, the rest should fall into place.

Do yourself a favor and get used to using the nute calculator at Cannastats to ensure proper ratios. I must have been getting some kind of lock out also as well as lack of N, so my nute mix was way off before when I just guessed. I now go by the Lucas formula and came up with a close enough mix with Botanicare brand nutes. I'm happy now and so are the plants, so far anyway.

Yeah I have been guessing so far with pretty good results but im not in flower yet. I know more def. will show however in flowering because it will take more energy to fix any def. on a budding plant. Im gonna try and apply the Lucas formula to my grow once i see the nutrient profile for the micro and the bloom. gonna have to work with what i got and adjust as needed. Thanks so much!