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wilma.flinstone

PH rising in RTW nutrient tank

Posted (edited)

Hello I have been having a problem for quite a while and have read nearly every forum I can find with no solution, So as the title says...I fill up my nutrient tank(with airstone) with RO water and I'm re-adding canna calmag and feeding canna A+B with CX regen-a-root and CX wilt guard.I will set my PH to 5.5 and within 17hrs it has raised to 6.0-6.1 up until now it hasn't really been a problem but I am away for a 4 days and I'm worried it will go past the point of a safe PH level. I've tried turning the airstone off...I've tried only adding A+B ...I've tried adding the PH down to water before mixing with nutrients...I've tried blocking up the small gap between the lid of the tank and the feed pipe...I just don't know what else to do and I have no idea why this keeps happening, because it's not even recirculating... the water is just sitting there in a dark closed of container at 25°c with a EC of 1.50 being aerated with an airstone  :wallbash: :wallbash:

Please can someone suggest something because all out of ideas and I'm away tomorrow and don't have much money to spend to buy a

Edited by Owderb
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Try Sensi nutes bud, Grow A+B and Bloom A+B....

No more expensive than any quality nutes and more to the point no ph adjustment, chuck the meter and ph down away...

If you're flowering use Buddha's Tree PK along with the above...:yep:

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14 minutes ago, stu914 said:

Try Sensi nutes bud, Grow A+B and Bloom A+B....

No more expensive than any quality nutes and more to the point no ph adjustment, chuck the meter and ph down away...

If you're flowering use Buddha's Tree PK along with the above...:yep:


Might look into that range next turn round but I got 10liters of canna A + B and I know people who run it with no problems...I really am lost for ideas....i'm away tomorrow And might just consider not feeding for the period im away....seems like my only option

 

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Posted (edited)

I was always under the impression that airstones will raise your ph, when I used canna nutes it would rise a tad in the first 24 hours but then stayed pretty still for the rest of the week. I would maybe try using a small water pump to break the suface of the water instead see if it makes a difference. Why are you choosing to use ro water?

 

atb

Edited by golf.007

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55 minutes ago, golf.007 said:

I was always under the impression that airstones will raise your ph, when I used canna nutes it would rise a tad in the first 24 hours but then stayed pretty still for the rest of the week. I would maybe try using a small water pump to break the suface of the water instead see if it makes a difference. Why are you choosing to use ro water?

 

atb

Because I read that RO water would help stabilise the PH ...I've been battling this problem for a while...

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What is the ph and ec of your tap water

 

Owd

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The pH of reverse osmosis water should be 7.0 at point of production. But this is short lived. Exposure to air causes atmospheric Carbon Dioxide to dissolve forming Carbonic Acid so when tested the pH is noticeably lower (more acidic).

 

Whilst I'm unfamiliar with the chemical composition of pH Up/Down liquids your using I suspect it's fairy elementary and offers no buffering effect. That is it's able to achieve a pH shift but unable to maintain/resist a further shift in pH due to other factors.

 

I'm wondering whether the continual stream of fresh air introduced via airstone is having an oxidative effect on the many additional additives you've introduced to the reverse osmosis water which over time is causing this slight but noticeable shift in pH towards alkalinity.

 

A good way to test this theory would be prepare a fresh solution, divide half into an air tight bottle (full, no air gap), half into the active airstone bucket. Leave in same environment for said period of time then test pH shift in both. If there is less of an pH shift in the sealed bottle then you have your answer.

 

 

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Owderb

I haven't really checked normal tap water tbh I always test after mix....I'm in work atm I left the tank at a ph of 5.95-5.98 ... I'll test tap water and RO water when I'm home...its probably too later to sort anything before I leave for holiday  tomoz....I'd still like to get it sorted for the future though.

 

Poisonata 

I'll do that first chance I get because I need to solve this problem, it's doing my head in :wallbash: I'll test plain water ph and see if that shifts when I set too 5.8 then add nutrients until I find the shift take place.Thanks guys

 

 

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Reverse Osmosis water will be more susceptible to pH changes as all potential natural buffering content, albeit minimal has been removed.

 

Hydroponic grows are uncharted waters for me. If the theory proves correct then I can only suggest collaboration with another hydroponic grower 'reverse osmosis recipe' to discover the offending supplement and/or alternatives.

 

Buffered solutions (resist pH change) tend to be narrow band (close to pH 7.0) using additives possibly a plant could tolerate. The greater the desired deviation from pH 7.0 the less likely a plant would withstand such additives.

 

My thoughts are purely from a scientific point of view so sadly resolution of your problem is unlikely to come from me. I wish you the very best :) 

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