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ph bounce
- Thread starter trev1212
- Start date
What type of growing medium and nutes are you using?
I think you may be trying to "guild a lily". ph is measured on a logarithmic scale. The differences between 6.0 (slightly acid) 7.0 (neural) and 8.0 (slightly alkaline) are so slight as to be insignificant. It can be difficult to measure in this range except by using carefully managed instruments.
The hydrogen and hydroxyl ion concentrations are so low that your breath passing over or through the solution can change the reading.
The scale goes up or down from the neutral point (7.0) by units of +1 or -1, but the significance of acid or alkaline 'strength' is X10 with each succeding point. ph 8 is x10 more alkaline than 7.0, ph 9.0 is x10 more alkaline than 8.0, ph 10 is x10 more alkaline than ph 9.0.
Therefore ph10.0 = 10 x 10 x 10 = 1,000 times more alkaline than ph 7.0
The hydrogen and hydroxyl ion concentrations are so low that your breath passing over or through the solution can change the reading.
The scale goes up or down from the neutral point (7.0) by units of +1 or -1, but the significance of acid or alkaline 'strength' is X10 with each succeding point. ph 8 is x10 more alkaline than 7.0, ph 9.0 is x10 more alkaline than 8.0, ph 10 is x10 more alkaline than ph 9.0.
Therefore ph10.0 = 10 x 10 x 10 = 1,000 times more alkaline than ph 7.0
Hi Trev,
I do agree with ZEBRA that pH is a ballpark estimate, and the exactness of the pH for hydroponics has been calculated more for economic control, than plant control these days, (although NASA/USAF did develop alot of "exactness"), for optimal uptake of nutrients....but to answer your question, it seems that your water is a bit hard, and it would require a bit more buffered acid to keep the pH lower. If your measuring equipment is accurate enough, keep adding a very buffered acid solution until you get your pH in the zone (normally 6-6,5 ish) It'll move alot, but don't worry too much about the swings unless you see it dive into the 4's or heave up to 9, then you'd want to change the water. (me, i would). There are cliffs to adding the buffered acid too. add 2x and get a drop of 1, and then add 1x more and it falls off the cliff...That's why I prefer to buffer the water to a stable pH first, and then add the nutrients, which should not move the pH too much one way or another. Th'as what I've found to be the case with all the plants that I've grown.
I do agree with ZEBRA that pH is a ballpark estimate, and the exactness of the pH for hydroponics has been calculated more for economic control, than plant control these days, (although NASA/USAF did develop alot of "exactness"), for optimal uptake of nutrients....but to answer your question, it seems that your water is a bit hard, and it would require a bit more buffered acid to keep the pH lower. If your measuring equipment is accurate enough, keep adding a very buffered acid solution until you get your pH in the zone (normally 6-6,5 ish) It'll move alot, but don't worry too much about the swings unless you see it dive into the 4's or heave up to 9, then you'd want to change the water. (me, i would). There are cliffs to adding the buffered acid too. add 2x and get a drop of 1, and then add 1x more and it falls off the cliff...That's why I prefer to buffer the water to a stable pH first, and then add the nutrients, which should not move the pH too much one way or another. Th'as what I've found to be the case with all the plants that I've grown.
do you have access to R.O. water? Some places are fortunate enough to live near a place that sells the stuff. I had to save up and buy one - best investment I made for my system.
Thats cool guys thanks for the advice..
I do use a pinpoint ph probe I used for breeding
My discus cichlids. Its pretty accurate. But if 7.5 is ok f
my hot pepper plants then awsome. Les work for me.
Also I have a ro unit. Works great. So adding acid before
nutrients is better than the other way around..
I do use a pinpoint ph probe I used for breeding
My discus cichlids. Its pretty accurate. But if 7.5 is ok f
my hot pepper plants then awsome. Les work for me.
Also I have a ro unit. Works great. So adding acid before
nutrients is better than the other way around..
I've found that as long as I change out my reservoirs weekly, ph swings aren't that big of a problem. When fresh my ph is a little on the low side, 7 dys later it's a tad high.
If you've got an accurate pH meter, than definately keep the pH between 6-6.5. Check out this table that gives an idea of why you want to keep the pH around under 7, but above 5.7.
http://flic.kr/p/dSAqC7
http://flic.kr/p/dSAqC7
That is an awesome chart. It really cleared a lot up for me. Thank you!
If you are thouroghly mixing your bucket before testing, you might consider mixing your acid solution with 250 ml of water before adding to the nutrient solution it is less of a shock to the system if you are using hydroponics. If you are using hydroponics it is completely normal for a ph fluctuation when the ph goes up it means the plants are up taking, I did a small experiment last year and kept mine at 5.5 to 6.5 and they were some of the biggest pods I have grown, however it was too much maintenance. If you are using a peat based media it is naturally acidic and you can get away with water at 7 or over but optimally for best results 6 to 6.5 is best if you are measuring the water. If you want to know whats going on with peat based media test some of the run off from a watering. If you have the technology use it.
so your nutrients ph is fluctuating without the plants help?
couple of things, bad meter. no atc, bad calibration... with no atc, your temperature must be the same for each measurement for consistant results.
carbon dioxide dissolved in water is acidic to some extent. if your muni water is stored in a hydro pneumatic tank it will dissolve co2 in very small amounts to form carbonic acid. its entirely unlikely it is responsible for a whoping 6-7.3 rise but it could be contributing. UNLESS you are taking the ph of a very very low alkalinity solution of say distilled water and very little else. once you have added your fertilizers you should have a decently alkaline solution.
your meter may need many minutes to stabilize, keep that in mine. my gel electrodes need like 2-3 minutes for a good reading, for soil slurries i let it go for like 20 minutes. your acid may be something crummy like vinegar. vinegar is an organic acid aka a carboxylic acid, i seem to remember that acetic acid can decompose in certain situations, idk what the details were, as i do not use vinegar for anything horticultural related.
alkalinity is measured in equivalent concentrations of carbonates keep that in mind..
couple of things, bad meter. no atc, bad calibration... with no atc, your temperature must be the same for each measurement for consistant results.
carbon dioxide dissolved in water is acidic to some extent. if your muni water is stored in a hydro pneumatic tank it will dissolve co2 in very small amounts to form carbonic acid. its entirely unlikely it is responsible for a whoping 6-7.3 rise but it could be contributing. UNLESS you are taking the ph of a very very low alkalinity solution of say distilled water and very little else. once you have added your fertilizers you should have a decently alkaline solution.
your meter may need many minutes to stabilize, keep that in mine. my gel electrodes need like 2-3 minutes for a good reading, for soil slurries i let it go for like 20 minutes. your acid may be something crummy like vinegar. vinegar is an organic acid aka a carboxylic acid, i seem to remember that acetic acid can decompose in certain situations, idk what the details were, as i do not use vinegar for anything horticultural related.
alkalinity is measured in equivalent concentrations of carbonates keep that in mind..