Losing control of PH 7 weeks in flower

[mazda3234wd]

Hey there guys and girls.

Ive been growing in DWC for a while now and am wondering if I'm getting root bound or Ive read somewhere if the rez isnt big enough then PH will not stabilize. I'm thinking my problem could be one of these things.

With this grow I have vegged for 1 month and now into week 7 of flower and have had no problems with PH up until now.
From the start till now PH has been starting at 5.8 going upto 6.2 within 3-4 days then goes back down to 5.8 over the next day or 2, then I change nutes and it does the cycle all over again...

About a week ago I'd do my res change and notice after 24 hours PH would be down at 4.7 so I got the shits and just gave her straight tap water which is a PH of 7.1. even after giving her straight tap water, PH 48 hours later still goes down into the 4's.

The only 2 things I think it could be is either root bound or res being to small, but I have no idea which is why I'm asking you guys.

The res is a 20 L bucket with a top I made and a 10" net pot. using hydrotron but the water isnt even touching the hydrotron, the bucket gets filled and drained from a hose going in through the top. there are also 4 large air stones in the res.

I use a locally made nutrient which has worked fine for years and I also have other systems using the same batch of nutrient as this bucket so I have ruled that out.
I can't actualy lift the plant to see the root ball cuz its just to big and annoying. I notice everytime I empty the bucket the water is very clear and clean. I do use a tiny bit of Oxy plus, about 1 ml per 10L but only do this every 2nd or 3rd nute change.

I will add pics so you guys get a better idea of what I'm talking about.

First pic is of the bucket setup I'm talking about. obvoisly not this grow. only pic I could find of the system.

2nd pic is of the bucket, hard to see anyting really, I just learnt how tricky it is taking pics in the dark hahaha.

3rd pic is looking down at the bucket, all you can really see are the 4 air lines going to it, but I generaly think the plant still looks healthy.. please let me know if I'm wrong.

One thing while I remember, ever since Ive lost control of PH ive noticed the buds re shooting new shitty growth, the F&D table i have right next to it with the same clone is finishing off great, very tight nugs, not shooting shitty new buds outa the top of the heads. I'm guessing this is just part of PH going crazy???

 

[Old_SSSC_Guy]

Might sound dumb, but you are not using hot water to mix your nutes, are you?

And regardless - your plants look happy and healthy. Looks like you're doing fine.

 

[mazda3234wd]

Not using hot water no, ALthough! since you say that I should ask this...

I have a flood and drain table now flushing, when i went to hook the hose onto the tap ive been using for years i learnt that my dad had taken it off to replace a washer so I used the hot water tap.
I thought this would be fine cuz the plants werent due for a drink for another 2 days.
Is it ok what I've done? the water is now cold as, 13c.

 

[Old_SSSC_Guy]

Not saying this is ->the<- reason, but using hot water or water that went through hot water pipes can mess up your pH. Hot water pipes can build up with a calcium scale, which is basically lime, and that would/could raise pH.

Just a wild guess... sorry.

 

[Grower13]

Makes me wonder if the ppm went way up when he used hot water. What are your ppm Mazda? I'd check the ppm of the hot vs cold water.

 

[mazda3234wd]

Heya

The res i used hot water on is a totally different plant. not the one having PH issues, sorry to confuse.
I did check PH and EC of the hot water the next day once it had cooled down and EC was at .2 same as my cold water. PH was 7.1 same as cold as well.

CHecked my bucket today and its PH was down at 4.1 lol once again I emptied and re filled with straight tap water only.
Im just glad that plant is in week 8, only thing shitting me is there isnt any color change yet and trichs are still clear as.

 

[Roddy]

Not saying this is ->the<- reason, but using hot water or water that went through hot water pipes can mess up your pH. Hot water pipes can build up with a calcium scale, which is basically lime, and that would/could raise pH.

Just a wild guess... sorry.

Very good info, THANKS! Wondering aloud...what is the reason calcium builds up in hot pipes and not cold?

I'd not have known this save for the great minds sharing in this site!!

 

[The Hemp Goddess]

Very good info, THANKS! Wondering aloud...what is the reason calcium builds up in hot pipes and not cold?

I'd not have known this save for the great minds sharing in this site!!

Actually, just the act of heating the water makes some of the minerals in the water break apart from the water molecules. All water heaters have an internal tube called an anode tube whose job it is to attract some of these minerals. That is also why you get deposits built up in the bottom of your water heater and why the hot water will usually freeze before the cold water (less dissolved solids). So bottom line is that water that has been through your water heater will generally have fewer dissolved minerals that your cold water.

 

[Grower13]

Actually, just the act of heating the water makes some of the minerals in the water break apart from the water molecules. All water heaters have an internal tube called an anode tube whose job it is to attract some of these minerals. That is also why you get deposits built up in the bottom of your water heater and why the hot water will usually freeze before the cold water (less dissolved solids). So bottom line is that water that has been through your water heater will generally have fewer dissolved minerals that your cold water.

I'm pretty sure I read about this in Ed's book.:icon_smile:

 

[Roddy]

Ok, think I'm lost here and I hate to ask a stupid question....but THG, are you agreeing with HP? Sorry, a bit slow on the uptake today....

 

[The Hemp Goddess]

Ok, think I'm lost here and I hate to ask a stupid question....but THG, are you agreeing with HP? Sorry, a bit slow on the uptake today....

LOL--I guess that I am slow on the uptake, too....."agreeing with HP" about what?

I was just trying to answer the question about hot water and mineral deposits.....

 

[Roddy]

Sorry SSSC and THG....wrong person....I meant are you agreeing with SSSC? No disrespect intended SSSC (or HP)!

Originally Posted by Old_SSSC_Guy
Not saying this is ->the<- reason, but using hot water or water that went through hot water pipes can mess up your pH. Hot water pipes can build up with a calcium scale, which is basically lime, and that would/could raise pH.

Just a wild guess... sorry.

 

[Hushpuppy]

I would be willing to bet that there isn't any problem with this setup other than the plant is gobbling up the nutes really fast and this is causing the PH to swing wildly. I suspect that when the plant was younger there weren't as many roots in the bottom, and now the rez is full of rootmass which is displacing a lot of the water which means you can't put as much water or nutes as you once could. Now that she is in the last stages and is still trying to produce buds(which are most likely foxtail buds), she is eating the nutes up in a little different manner than before. I have this same issue happening to me when my plants chang over from vegging to flowering. The PH drifts one direction while in veg then another when in flower (and this action will vary with different strains).

 

[ozzydiodude]

Bum up the feed and get your plants a bumping

 

[mazda3234wd]

CHeers guys for the replies.

Hushpuppy I reckon you are spot on!.

Do you think I'm better off having an external res next grow? I grow buckets next to coco tables and I just how much more vigerious the growth is in buckets. Just the PH issues give me the shits. Love coco, she jsut stays around 5.8 the whole grow.

I changed water over again today, was down at 4.8 PH, our tap water is up in the 9's atm so thats what shes been getting.

Can someone explian how the hell the plant is not getting sick with the PH going crazy like it is? from 8.9 to 4.2 within 2 days.

 

[Hushpuppy]

Having the PH swinging is not necessarily a bad thing. It certainly will make one nervous, and we would prefer that it stay more steady than that. But when the PH swings like that it means that there is a lot of activity happening within the plants and within the rez itself. Different chemicals are absorbed by the plant at different levels of PH, but they all are relatively available to the plants (in hydro or soilless) around 5.8, so we prefer that it stays close to that. The truth of that shows in that the plant looks quite healthy, which means it is getting what it needs, maybe just not enough to keep it steady.

You say that she is in week 7 of flowering, then it is not suprising that she is gobbling up the nutrients from every batch of water that you put in. Having a larger rez would certainly help that issue. However, I have 30L rez under my plants which feeds 4 plants that sit in smaller totes that each hold about 1L, giving about 30-35L all the time and I still have PH swing as well. It just happens sometimes with different plant strains that are nute hogs and different mediums.

The one thing that I would say to do different at this point is: if you haven't added any nutrients to this fresh watering, then drain it and run straight water without adjusting the PH and let it run for about an hour. Then drain it out and run just straight water again and let it run for an hour again. then drain it and this time add back your water with nutrients but increase the nutrients by about 25%, adjust your PH and see what she does. I bet the PH will stay steady longer and you will see the buds start to really swell.

After a few days, look closely at the tips of the leaves to see if they are starting to burn. If they show no burn after a week, then when you do the water again increase the nutes again by 20% and let go for another week. If you see leaf tips starting to burn then at the next time you add water, don't add any nutes so that the straight water will dilute the nutes that are there some. Let us know how it goes

 

[Kushluvr]

it sounds like root rot to me! pythium maybe...........this happens when there are to many roots and its bound! not enough oxygen in the water!

in hydro, water temp and oxygen are extremely important!

64F water and lots of air flow........thus why the under current systems are top notch!

do u have a water chiller? other than aerating, is the water recirculating?

even running a sterile aqua culture wont help!


pretty standard complaint for DWC late in flower! your FND tables roots arent hanging in the water 24/7 thus why there ok!!

good luck....not much you can do at this point but bear down and hold on for as long as you can! however flavor and potency can be effected severely!