Super low ph runoff-What is causing this??

[spreadhead]

i am kind of new to coco growing. i have been doing it about a year. i use 1 gallon grow bags, botinicare coco, advance nutrients 3 part, hydgrozyme, earth ambrosia & earth nectar. nothing special...
i use distilled water i get from those glacier machines. the ph of this water is about 6.3.
i grow under a 150hps in a small cabinet. i have been growing for 10 years mostly in water but high temps brought me to coco.
i have two plants flowering and they booth started going downhill. i could not figure out what it was so I checked my run-off ph of the worst plant and it was 3.5....so i started freaking out..checked the second and it too was 3.5...i checked my water and it was holding at 6.5. i immediately started flushing and got no change in the ph run off. i then added a couple of tablespoons of pelletized lime...What do I do now? Should I continue to flush? Is the lime a good idea? i am panicking. what could be causing such a low ph?
Please help...some other information is I have a soil ph meter and when i stick it in the grow bags it says 7.0 but i have never trusted this meter...it seems it always reads 7.0...also I re-use my coco but only the coco that easily falls from the roots when i finished and only use it sparsely to top off a bag or to use when potting newly rooted clones.
in all of my years i have never had a ph problem...i was under the impression if i was using ph balanced water i would be ok..

 

[clp]

Well what's the PH of your nute mix + water? Maybe you need to raise PH before watering..?

That is extremely low and needs to be fixed ASAP!

 

[MarquisBlack]

What does the damage look like on the foliage?

Runoff pH in coco is unreliable, however, acidic runoff should be considered a possible symptom of rot.

 

[areUkind]

What does the damage look like on the foliage?

Runoff pH in coco is unreliable, however, acidic runoff should be considered a possible symptom of rot.

how would one check the ph of the coco if you do did not water to drain waste?

 

[SGMeds]

Don't know why there isn't a sticky just for this issue...???

I've run coir for a long while & love it... my favorite medium. But the 2 things that are consistently noticed are:
1. high initial ppms for run-off
2. low initial pH for run-off

Never actually seen it in the 3's, but low to mid 4's is common.


Don't know the exact science of it, but my gut tells me that at first the coir is sucking up certain cations & displacing a lot of the stored up junk it previously had in it... trying to reach a new buffer with the nutes we are feeding it.

The result from this exchange is high ppm's & low pH. Usually like this the first week or two, then all becomes well balanced... and super easy to run.

Flush a lot before you plant.

Use a shit-ton of Dolomite Lime for the first week... mix 1-2tblspn per 5gal of solution... pH should be up over 6.5-6.8, depending on u'r mix. DL buffers the pH very well. Get finely pulverized powder (don't breath) as it gets into the coir easily. Run twice the volume to run-off as you usually would.

u'r pH at run-off will up noticeably. then repeat as necessary to raise it to the levels you want. keep adding a little DL for the rest of the week, then you can effectively drop it entirely. quick & easy fix. peace

 

[fred b]

hmm i dunno but i use canna coco and my drain ph is the same as my rez ph. the ec is usually lower than the rez ec. here i can see if the plants are actually consuming nutrients. when i see a higher ec or a different ph than the rez i flush the coco with ph adjusted water.

greets
fred b.

 

[spreadhead]

the ph with nutes added is about 6.5...i use a liquid ph kit so it is .5 measurments...i did not have any dolomite lime but had granualr...i am thinking i will mix with water instead of soil so i can dissolve and get it to the plants quicker..

 

[buddin_904]

considering i dont believe in checking run off pH....but in your case if its THAT low....sounds like a build up of acidic nutrients....are your plants excessively GREEN????...curling leaves downwards???? REGARDLESS>>>>ASAP flush your pots with regular water, which would raise the rootzone pH and then start over and water through a fresh batch of mixed nutes.

 

[Carl Carlson]

how would one check the ph of the coco if you do did not water to drain waste?

That's a great question.

Nursery discovers value of "pour-through" testing

Before Vissman discovered pour-through, Greenleaf used to do its own in-house testing. “We purchased simple kits that measured some elements as well as pH and conductivity. The tests were quick and fairly inexpensive. They would have been worthwhile had the results been straightforward and accurate, but, as it was, their subjectivity and margin of error didn’t justify the cost.”​

PourThru Sampling

Similar in technique, but not on the bottom line.

 

[spreadhead]

budding 904..i have never checked my run off but one plant had symptoms of ph problems or nute lock out..leaves curled downward splotchy yellow..very similar to this
http://www.onlinepot.org/grow/PHfluctuationsornutrients3.htm

so i guess i did not believe in checking run off ph either until i had this problem problem.

do you use lime to stabilize ph...i did not believe in this either until i had this problem


i flushed again this evening and the run off seems to be creeping


Carl C...that is some good information..thanks

 

[TanzanianMagic]

i use distilled water i get from those glacier machines. the ph of this water is about 6.3.

Distilled water has no ph buffer, unlike tapwater with lots of calcium in it. For instance when you ph 8.0 tapwater to 6.0, and come back a few hours later, it will be back at 8.0 again. The second time you ph it to 6.0, you'll notice you need to use a lot less acid, because the acid has been absorbed and reduced the buffering capacity.

Nutrient solutions are very often made for high ph/calcium water, and are acidic. So when you add nutrients intended for high ph water, the ph is going to be very low. (A lot lower than 6.5 or 6.3.)

The only other thing I can think of is that rotting roots are lowering the ph, or something with how you measure the ph. I suggest investing in a real electronic ph (and ec) meter. You should let it stand in distilled water for a few days, so you get an instant readout.

 

[buddin_904]

stop using RO water.....tap will give you a more highly stable higher pH value.....

but since u decided to check run off pH for the 1st time, something caused you 2 do this...the lockout deficiencys on the leaf......i ususally just go for the read the leaf approach....but in your case it was valuable to find out of it was overly high or overly low in your case....so now that you no its low....regardless of number you should take steps in ensuring it doesnt ever get low again...honestly i dont no how you feel about it, but tap water should be your solution 2 this problem......

and i dont use dolomite lime because i just use tap and it supplys enough calcium and buffer for me

 

[spreadhead]

thanks buddin904...i have always used distilled water...when i was running a dwc and now with coco...i do not completely understand the buffer aspect but i do understand a plants ability to uptake nutrients optimally has to do with the ph... i can tell you with my glacier water vending machine at the trusty foodlion i can take the ph of the water that has set for a while and it will be kind of low...then i will shake it up and it levels out at 6 to 6.5...i have never cared about ph because i have never had this problem but once i stated down the ph road i have taken readings of everything...today my run-off was 5.0...i can live with that but i am pretty sure i have lost one plant and because i do a microgrow this sets me back...when you use tap water do you use ph down...i suspect you do not use a root enhancer either because the clorine kills all the bene's bacteria

btw...no rotting roots...pulled the grow bag off and things look health

 

[buddin_904]

the trick is 2 let the tap water sit with an uncovered top for a couple days.....the cl(gas) will evaporate out vitually disapeering.....i used to use distilled too, then 50/50 distill/tap....now straight tap.....for my particular nutrient i actually need to add a dash of acid.....but its different for each product...your product may be very acidic....

 

[spreadhead]

thanks buddin...i use advance nutrients 3 part...i noticed during the flush that the water had a pink tint...like the flower part of the 3 part...i also do not water until i get run off...until now..a while back i did the 50/50 thing then straight tap after putting an airstone in it for a couple days...then i had a problem with super high ph and went back to distilled

 

[jackiee]

i would calibrate your meter especially if you dont trust it ? after that take a true reading and adjust things from there just my opinion.stay lucky

 

[buddin_904]

^ yea definately recalibrate your meter.....i definately advocate this

 

[buddin_904]

use buffer solution too...the 7.01 ....not anything else....i guess you could do it with 4 and 7 if your meter allows for that....

 

[spreadhead]

no meter..a liquid..3 drops into water sample...everyone knocks it but i trust the process and my readings..did noice ph fell with addition of nutes...added tap water and leveled off at 6.0

 

[buddin_904]

oooooo sneakin that tap in.....lol