What is the reason for pH of nutrient solution to go up drastically over night? Please help!

[BibbyMcBuds]

Hi all, Hope everyone had a great Christmas.
I really need help figuring out why the pH in my nutrient solution to go up over night by 3 to 4 points over night? Everything I'm seeing online only explains pH going down due to organic materials or temperature ect. Nothing about how or why it could be increasing. It is making the process of feeding a much longer experience than it should be. For example if I leave my nutrient solution in my 10 litre container at pH 5.7 over night the pH will change when I test it the next day to 6.0 or if I leave it at 5.9 it changes to 6.2 or like last night it was 6.0 but today it was 6.4 so I had to lower it again. What is the reason for this? Because I keep having to change the pH if it's not in range anymore before I feed & that's the reason why I pre make it so I can just feed them when I don't have time. The temperature does rise a bit by 2 degrees but this should decrease the pH. I'm stumped. If anyone knows the answer to this please let me know. Thanks everyone

 

[Fangthane]

Could be from hard water or some property of your nutrient line. A few points of pH swing isn't really an issue, since there's a range at which different nutrients can be absorbed and used. A lot of growers allow their solution to drift a bit to make sure they utilize more of that range. The 1 time I did DWC, I had drastic pH spikes, like from 6 to 8 within hours. Now THAT can be a problem.

 

[warble]

Different plants use different amounts of nutes. Size of plants also matters. Bigger plants will change your Ph quicker. I use at least 15L per plant, but I also veg for more than a month. Higher temps in your solution will also increase your Ph. What kind of humidity are you dealing with? Then there could be bugs, that affect Ph.

 

[OldMedUser]

Hi all, Hope everyone had a great Christmas.
I really need help figuring out why the pH in my nutrient solution to go up over night by 3 to 4 points over night? Everything I'm seeing online only explains pH going down due to organic materials or temperature ect. Nothing about how or why it could be increasing. It is making the process of feeding a much longer experience than it should be. For example if I leave my nutrient solution in my 10 litre container at pH 5.7 over night the pH will change when I test it the next day to 6.0 or if I leave it at 5.9 it changes to 6.2 or like last night it was 6.0 but today it was 6.4 so I had to lower it again. What is the reason for this? Because I keep having to change the pH if it's not in range anymore before I feed & that's the reason why I pre make it so I can just feed them when I don't have time. The temperature does rise a bit by 2 degrees but this should decrease the pH. I'm stumped. If anyone knows the answer to this please let me know. Thanks everyone

What water are you using? Hard tap water will cause pH to rise after adjustment as un-reacted carbonates re-populate the sol'n with ions raising the pH. I gather this is while the mix is still in a storage container so plants are not affecting the pH.

When I was doing DWC I would adjust to around 5.5 every 3 days when I topped up my tubs with RO or distilled water. Top up with water first and wait 15 min or more to allow good mixing from the bubbles. Check ppm and add small amounts of nutes to get it back up to target, allow mixing then check pH which was almost always 6.2 - 6.3 so 4 or 5 drops of sulphuric acid would knock the 50L of mix back to around 5.5. Plants loved that action.

Then I ran out of my older style AN 3-part nutes and got the new ones with pH Perfect tech. Never even thought about pH after my first tub using it. Made growing so much easier and the plants loved it. Works great in pots full of ProMix HP too. I did about 50 tubs worth of DWC growing from '01 - about '19 so tried all sorts of things in that time. You can make any nutes work but being a lazy old fart I want the easiest route to get lots of bud and those nutes are the bomb.

I once kept track of how much nutes, power and water I used for a whole 2-tub grow and with my power costing around 26¢/kwh at the time the nutes were 5% of my total costs to grow 2 lbs of pot. The RO water I bought at $3.49 for 5USG each cost way more than the nutes. When I bought the 3 - 1gal jugs of nutes it was $40 less than the same amount of GH 3-part and those came with the joy of screwing around with pH. I still have almost half those jugs left that are at least 7 years old now but I'm still using them with no issues.

 

[BibbyMcBuds]

Could be from hard water or some property of your nutrient line. A few points of pH swing isn't really an issue, since there's a range at which different nutrients can be absorbed and used. A lot of growers allow their solution to drift a bit to make sure they utilize more of that range. The 1 time I did DWC, I had drastic pH spikes, like from 6 to 8 within hours. Now THAT can be a problem.

Wow 6 to 8 is crazy. That would have been a big problem for sure. I just use tap water, I didn't actually think of that because I've always been told to make sure it's between 5.8 & 6.2 but that's a good point different nutrients are absorbed better at different pH. I've started making them up the night before lower at like 5.6 so it's been evening out but I just wonder what actually does it, my tap water has smelt quite a bit more chlorine like lately. Thanks for your info, always keen to hear from other growers

 

[BibbyMcBuds]

Different plants use different amounts of nutes. Size of plants also matters. Bigger plants will change your Ph quicker. I use at least 15L per plant, but I also veg for more than a month. Higher temps in your solution will also increase your Ph. What kind of humidity are you dealing with? Then there could be bugs, that affect Ph.

Hi again Warble! I was actually wondering how long to veg for, I'm at week 5 now I think, was thinking doing 6 weeks, is that about how long you veg for or do you go longer? You use 15litre per plant?! I'm only feeding 5 litres in a 5 gallon with heaps of runoff. What size pots? Am I feeding too little? Well the pH isnt changing in the Coco thank goodness, it's changing in the actual container before I feed it to the plants. I make it up the night before so I don't have to muck around in the morning making it up coz it's Coco I have to feed everyday & I didn't realise the pH was changing in the container over night so I was feeding my plants the wrong pH for a few days before I realised which made the plants go a bit funny. I've started doing it at about 5.7 so it evens out by the time I use it to 6 or 6.2 which is in range but I just wonder why it's changing. The temperature does in the nutes does go up to about 23 over night because it's quite hot here in Melbourne right now, it starts at about 19 degrees. Maybe that's what is changing it so much. It sometimes takes me 2 hours to make the nutes up for only two plants, one baby auto one 5 weeks photo. The auto is to go outside in greenhouse before I switch the photo to 12/12. I use quite a few different nutes so that's why it takes me so long plus I'm new, I'm at ppm 1150 now which she's taking well, she's growing rapidly. I did a pretty full on de foliation last night to make sure the nodes get lots of light. Hope your plants are doing awesome! Thanks again

 

[BibbyMcBuds]

What water are you using? Hard tap water will cause pH to rise after adjustment as un-reacted carbonates re-populate the sol'n with ions raising the pH. I gather this is while the mix is still in a storage container so plants are not affecting the pH.

When I was doing DWC I would adjust to around 5.5 every 3 days when I topped up my tubs with RO or distilled water. Top up with water first and wait 15 min or more to allow good mixing from the bubbles. Check ppm and add small amounts of nutes to get it back up to target, allow mixing then check pH which was almost always 6.2 - 6.3 so 4 or 5 drops of sulphuric acid would knock the 50L of mix back to around 5.5. Plants loved that action.

Then I ran out of my older style AN 3-part nutes and got the new ones with pH Perfect tech. Never even thought about pH after my first tub using it. Made growing so much easier and the plants loved it. Works great in pots full of ProMix HP too. I did about 50 tubs worth of DWC growing from '01 - about '19 so tried all sorts of things in that time. You can make any nutes work but being a lazy old fart I want the easiest route to get lots of bud and those nutes are the bomb.

I once kept track of how much nutes, power and water I used for a whole 2-tub grow and with my power costing around 26¢/kwh at the time the nutes were 5% of my total costs to grow 2 lbs of pot. The RO water I bought at $3.49 for 5USG each cost way more than the nutes. When I bought the 3 - 1gal jugs of nutes it was $40 less than the same amount of GH 3-part and those came with the joy of screwing around with pH. I still have almost half those jugs left that are at least 7 years old now but I'm still using them with no issues.

Hey, I use regular tap water but the tap water here in Melbourne is very good as far as I'm aware but it has been smelling more chlorine like lately. Yeah it's changing inside the container which it never did the last grow I did so I was wondering what's going on. Obviously it's something I can deal with but it's just annoying & I'm lazy as so I'm hoping if I figured out what was doing it I don't have to bugger around all the time once I've already made them up you know. Plus if I've used pH up but have to use pH down to get it right I have to start over because I read you can't use both which makes sense. I didn't think of using the actual nutes to lower the pH, that's a good idea but I don't think I could use them to up the pH. I'm going to look into that pH perfect tech, that sounds awesome thanks for the tip. Never heard of it but growing isn't big here so that's probs why. I'm lazy as too so easy route is definitely what I want lol. I'm thinking I may have made a mistake buying a $250 full kit of 1litre & 250ml nute bottles of bio diesel but I guess we will find out how well they work at harvest. They make them here which is unusual since it's illegal so I was trying to go local. Wish I could grow 2 pounds of pot, most Ive got is just over 200 grams, I have no room here but hopefully going to get more than 200 this time. Thanks heaps for all your advice, your time is much appreciated

 

[warble]

Hello BibbyMc,
Do you let the tap water sit for a couple of days? The water getting warm overnight is not helping the Ph. Are you aerating the solution overnite? A small fish tank bubbler would be fine for fifteen litres. I use five gallon fabric grow bags. I try to get a gallon of runoff in each plant. If you're having some salt build up problems, you should get more runoff than that.
A quick fix for your nutes, could be to throw in a frozen water bottle, by the time you use it, the temp should still be cool. You want it between eighteen and twentytwo. Twenty three is too high. You could be dealing with some root rot. That is an easy fix for dwc, not so much for soil.
Since you just defoliated, you might wanna knock down those PPMs. If she doesn't present tip burn, you can up the PPMs. I don't go that high, for veg, but if you are getting away with it, rock on. I max out five-hundred PPMs for veg, and nine-hundred for flower. I'm not growing sequoias, I have maybe three foot bushes.
I veg for months. pull a couple of cuttings maybe twice and use one of the clones as a new mother and then flower the older plant.
As for being lazy, that is for smoking weed, but growing, I'm not one to advocate for that. I figure I'm not the smartest, or wealthy, so I put in the effort and attention. From seed, veg, clone, flower, pest control, harvest, dry and cure, I take my time and am very frugal with my nutes, space, and electricity. You will find easier ways to getter done, but while you are honing your process, make some mistakes, learn from them and others. You are on the right path. Keep up the good work and good luck.

 

[Lou66]

There are two possibilities. One is CO2 off gassing. It reacts acid with water and lowers the pH. As it escapes there is less acid around so the pH rises. This drift should be done after about one day if the solution is properly agitated.

The other possibility is microbial growth. I have seen that increase the pH. This happens if you use organic nutrients (or nutrients with organic stabilizers). I use organic in the technical sense meaning molecules that contain carbon. The carbon is metabolized and various nutrients consumed along side.

I don't know if you do drain to waste or a recirculating system? Roots sequester a lot of sugar and other organics that feed microbial populations. Combined with the uptake of nutrients this affects pH in recirculating systems.

 

[OldMedUser]

Hey, I use regular tap water but the tap water here in Melbourne is very good as far as I'm aware but it has been smelling more chlorine like lately. Yeah it's changing inside the container which it never did the last grow I did so I was wondering what's going on. Obviously it's something I can deal with but it's just annoying & I'm lazy as so I'm hoping if I figured out what was doing it I don't have to bugger around all the time once I've already made them up you know. Plus if I've used pH up but have to use pH down to get it right I have to start over because I read you can't use both which makes sense. I didn't think of using the actual nutes to lower the pH, that's a good idea but I don't think I could use them to up the pH. I'm going to look into that pH perfect tech, that sounds awesome thanks for the tip. Never heard of it but growing isn't big here so that's probs why. I'm lazy as too so easy route is definitely what I want lol. I'm thinking I may have made a mistake buying a $250 full kit of 1litre & 250ml nute bottles of bio diesel but I guess we will find out how well they work at harvest. They make them here which is unusual since it's illegal so I was trying to go local. Wish I could grow 2 pounds of pot, most Ive got is just over 200 grams, I have no room here but hopefully going to get more than 200 this time. Thanks heaps for all your advice, your time is much appreciated

You can use both if you have too but you should always add whatever nutes you are going to use, mix well and allow 15 min or more to stabilize before checking and adjusting pH. That's why I like the AN nutes with RO water. Never have to think about the pH at all. They also have some supplements built in tho other nutes work just fine once you get used to using them.

If you need to use pH up I'd get some potassium silicate for that. Works great and the silica is good for the plants. pH down is usually 10% phosphoric acid. I use conc, 96%, sulphuric acid for that. Not car battery acid as that's not clean.

I generally only get around 3oz of pot off each plant grown in pots. A lot of what I see guys reporting is either flat out lies or wet weights as the plants I see them claiming the weights from are no bigger than ones I've grown with my 3oz. Some even count the weight of the pot I think.