Grow Mediums What should I do to stop water stagnating?

[SweetSkunk]

Hi all,

I'm currently doing a Coco grow for only the second time and it's been a good few years since the first.

I have a 150L water butt (approx size) that gets filled up with tap water, left to sit for a day or two before using.

I'm worried the water is going stagnant as it is not getting moved about at all.

I was considering putting an air stone in the water for the sole purpose of movement and to prevent stagnation.

however the PH of the water is already high and continues increasing as the amount of time the water sits in the butt increases (up to 7.5-7.7).

I don't want the air stone to increase my pH further requiring more PH down and thus have come looking for the forums advise.

any ideas?
cheers
SS

 

[Bob's Auto's]

Hello SweetSkunk,

You should put something in the water to keep it moving. An airstone is a great way. It does three things. Increase oxygen, move the water and keeps your nutrients mixed.
You will also need something to lower your pH. Sulfuric acid is a good one to have. With that also comes a pH pen and while your at it also buy an EC pen so you can measure the nutrient content of your solution.

Regards,

Bob

 

[BII]

What is the problem with pure water just sitting in a container? As 'pure' tap water, it shouldn't have soluble organics, shouldn't be able to support fungal or bacterial fermentation, or whatever your concern is.

Mosquitos larvae in the stagnant water is the main risk. But I presume every grower is already adding a Bt product to their feed water to kill insect larvae. Algae growth is another risk, although more of a mess vs. affecting the water, so make sure the water is protected from light exposure.

Otherwise, theoretically, aerating water should result in more CO2 dissolved in the water, forming more carbolic acid, and reducing the pH, not raising it.

Others who bother to adjust pH (I manage not to) can perhaps comment on whether you should be adjusting pH of the stored water or just do it as you mix feed.

 

[Mizzo81]

I have no issues leaving RO water in a container I cover and keep dark. When ready use it and all is fine.

 

[SweetSkunk]

What is the problem with pure water just sitting in a container? As 'pure' tap water, it shouldn't have soluble organics, shouldn't be able to support fungal or bacterial fermentation, or whatever your concern is.

Mosquitos larvae in the stagnant water is the main risk. But I presume every grower is already adding a Bt product to their feed water to kill insect larvae. Algae growth is another risk, although more of a mess vs. affecting the water, so make sure the water is protected from light exposure.

Otherwise, theoretically, aerating water should result in more CO2 dissolved in the water, forming more carbolic acid, and reducing the pH, not raising it.

Others who bother to adjust pH (I manage not to) can perhaps comment on whether you should be adjusting pH of the stored water or just do it as you mix feed.

Thanks for your reply my man.

As we had a little delay at germination stage, the water was left in the container (inside a garage so no light exposure) and by the time I came to use it, it had a film on top and just seemed off to me. I then began to think i may have issues with the water if I don't do something about giving it some movement.

I have hard water here with a E.C of about 0.5. my pH increase to about 7.9 once left for about 7 days so it's a must for pH down.

I hand feed and mix nutes in a bucket. the water storage is simply convinience.

if the air would decrease my pH, then this may be a sensible thing to do for that alone?

cheers for you advice
SS

EDIT:
I'm doing nothing in regards to mosquito larvae. what's is "BT"?

 

[SweetSkunk]

Hello SweetSkunk,

You should put something in the water to keep it moving. An airstone is a great way. It does three things. Increase oxygen, move the water and keeps your nutrients mixed.
You will also need something to lower your pH. Sulfuric acid is a good one to have. With that also comes a pH pen and while your at it also buy an EC pen so you can measure the nutrient content of your solution.

Regards,

Bob

Cheers Bob.
I have all the above mentioned, just not an air stone

 

[Bob's Auto's]

I hand feed and mix nutes in a bucket. the water storage is simply convinience

If you're not using the water storage vessel for anything else I would recomend you premix everything in there and add an airstone. It's much easier to regulate a large quantity then a smaller (10L bucket) one.
Also because of the hard water you have you'll most likely notice that the water in the large container doesn't keep it's pH steady for the first couple of days. This also happens in your medium with the disadvantage that it's not easily corrected.
What I would do is... Fill the vessel with 120L of water and add about 10ml of Sulfuric acid. Put your airstone into that and let it bubble away for a couple of hours. Then measure the contents. If the pH is lower then 6.5 add more water until the pH is 6.5 ish and note that you use less Sulfuric acid the next time.
Now the next day you measure the tank again and you'll probably will notice that the pH has risen. This is normal as the Calcium in the water reacts with the acid. It's doing it's job buffering the pH. When the pH is stable you can procede with adding nutrients in the tank or continue by adding them in the bucket. I recomend adding them in the large vessel.
The most important thing is to take notes...
How much water added. Amount of acid added and so on. Once you've got this dialed in you'll know how much acid you'll need to pH down your water so the outcome in 24h is always the pH you want

Regards,

Bob

 

[BII]

....

I'm doing nothing in regards to mosquito larvae. what's is "BT"?

Stagnant water can attract mosquitos and similar insects that hatch their larvae in water. Bt refers to toxins produced by Bacillus thuringiensis soil bacteria, toxic to mosquito and other insect larvae, non-pathogenic to animals, and usually even considered 'organic,' used for 'biological' mosquito control.

In my view, Bt should be added to every reservoir, all feed water, every time, to prevent larvae either in the water or laid by insects in the media/soil from eating young roots or the grown insects just being a nuisance (if they don't eat live plants). I found it particularly needed with coco. If Bt is used, you don't need to play games with less direct methods, such adding diatomaceous earth (sharp silicate crystal) to the top of the media/soil.

Bt products are common, should be in garden centers and even hardware stores. Common forms are solid time-release 'mosquito dunks' thrown into ponds/standing water (including reservoirs) to prevent larvae growth, and popular liquid formulations, such as Captain Jack's Deadbug Brew. I use Microbe-Lift/BMC, probably the most concentrated product - very cost effective (bottle lasts >year or years), only use a few drops at a time.

 

[SweetSkunk]

If you're not using the water storage vessel for anything else I would recomend you premix everything in there and add an airstone. It's much easier to regulate a large quantity then a smaller (10L bucket) one.
Also because of the hard water you have you'll most likely notice that the water in the large container doesn't keep it's pH steady for the first couple of days. This also happens in your medium with the disadvantage that it's not easily corrected.
What I would do is... Fill the vessel with 120L of water and add about 10ml of Sulfuric acid. Put your airstone into that and let it bubble away for a couple of hours. Then measure the contents. If the pH is lower then 6.5 add more water until the pH is 6.5 ish and note that you use less Sulfuric acid the next time.
Now the next day you measure the tank again and you'll probably will notice that the pH has risen. This is normal as the Calcium in the water reacts with the acid. It's doing it's job buffering the pH. When the pH is stable you can procede with adding nutrients in the tank or continue by adding them in the bucket. I recomend adding them in the large vessel.
The most important thing is to take notes...
How much water added. Amount of acid added and so on. Once you've got this dialed in you'll know how much acid you'll need to pH down your water so the outcome in 24h is always the pH you want

Regards,

Bob

thanks for your advice.
I was going to do as you suggested and add the pH down directly to my res, however, I thought about it a bit more and realised I always add nutes before pH down as the nutes reduce the pH themselves

have any thoughts?

I've got some air pumps and stones and will be adding them tonight !

cheers my man

 

[Bob's Auto's]

have any thoughts?

Glad you asked. That's why I said fill the tank up to 120L in stead of 150 and why I would adjust the pH to 6.5.
If you're in Hydro or Coco You can still go down and if you're growing in soil just add water to go up

I'll give my setup as an example.

This season I'm growing in buffered Coco with 30% Perlite added to it. So my range for pH would be 5.5 - 6.2.
My nutrient tank is 60L Which in hindsight is on the low side, but that's an issue for next season.
While I'm filling the tank with tap water (pH 7.8 EC 0.18) I add between 12 and 16ml of acid. 12ml if I want the end result to be pH 6.0 and 16ml if I want it to be 5.5.
Then I add 6ml Potsil or in my case Potassium Silicate (which is wayway cheaper). This will counteract the amount of acid as Potassium Silicate has a very high pH. Then I add my A+B nutrients.
By the time I have everything added my tank is almost full and it's time to measure. I stop adding water so I have room to spare in case the pH is to low so I can add more water and have a syringe ready with a couple of ml Sulfuric acid in it to lower it if needed.
Then top of the tank so it's completely full and let the airstone do it's thing.
The next day in the morning I measure the pH and EC again and adjust.
You'll get the hang of it. Just make notes of everything you've added and compare after you're done. I can't stress that last one enough

Oh, one note (and it's an important one)... Adding acid isn't something that's linear. What I mean by that is that if you need (for example) 10ml of acid for 50L of water to change from pH 8 to 6 and you add 10L of water to the already pH lowered tank you would need 2ml more to come to the same result. That's not the case. There's all sorts of of chemical reactions taking place one being the Calcium carbonate which is added by the water company to buffer your water and those need to be accounted for. So in the beginning take it easy with adding acid to your tank or you'll need to throw half of it away just so you can add more water to raise the pH again. Just note how much you've added and calculate when you're done. After a couple of days making notes use the average and test it out. You'll be amazed how fast you can accurately mix your 150L tank

Regards,

Bob