Shelf life of H2O & nutrients

[growsomebud]

Hi all, just wandering, I mix Fox Farms and Cal Mag in distilled water. I've had some mixed water left after some feedings, and I've wondered what the shelf life might be of the unused water. Would it be OK to use it, say ten days later along w/ a new batch of water and nutes. I say ten days cuz there would be just a watering in between.

I also wonder how much water would be appropriate to feed this plant in a 5 gal bucket(w/ holes made in the bottom, of course). The soil is some basic potting soil w/ most if not all incorporated nutes used up by now.

 

[growsomebud]

re: Shelf life of H2O & nutrients

I should add that it's about 30% bigger than this since pic was taken.

 

[iwltfum]

re: Shelf life of H2O & nutrients

If you bubble the nutrients constantly with an air stone and pump, then the nutrients will last 10 days maximum. If the water is stagnant, I would not use the water if it has sat for more than 24hours.

A five gallon bucket with soil in it should take around 3-4 gallons of water - give or take depending on how absorbent the medium is. You want to make sure you water slowly enough for the medium to completely absorb the water and you want around 20-30% of the water to run out of the bottom of the pot and to drain away from the soil so the roots aren't sitting in water

 

[growsomebud]

re: Shelf life of H2O & nutrients

Oh, wow, I had put in a full gallon this morning with plans to come back an hour later so I could check the run offs pH. I had a dry pan.

 

[Mayne]

re: Shelf life of H2O & nutrients

and dont use distilled water, RO is the way to go.

 

[growsomebud]

re: Shelf life of H2O & nutrients

and dont use distilled water, RO is the way to go.

Explain, please.

 

[Scientific]

re: Shelf life of H2O & nutrients

Explain, please.

RO water should be cheaper than distilled because it doesn't have to be boiled.

With all due respect to the previous posters, I personally don't see any reason why the mixed ingredients shouldn't last indefinitely if kept sealed in a cool, dark place. It's just mineral salts in solution, after all--liquid fertilizer.

The one important thing is to mix nutes in the correct order. General Hydroponics recommends adding Calcium/Magnesium first. I think that's because it's an alkaline solution and the rest are acidic. In the GH world, you add micro nutrients next, then the rest in any order. Check with your manufacturer's website to be sure. I'll bet adding Ca/Mg first is universal though.

 

[growsomebud]

re: Shelf life of H2O & nutrients

RO water should be cheaper than distilled because it doesn't have to be boiled.

With all due respect to the previous posters, I personally don't see any reason why the mixed ingredients shouldn't last indefinitely if kept sealed in a cool, dark place. It's just mineral salts in solution, after all--liquid fertilizer.

The one important thing is to mix nutes in the correct order. General Hydroponics recommends adding Calcium/Magnesium first. I think that's because it's an alkaline solution and the rest are acidic. In the GH world, you add micro nutrients next, then the rest in any order. Check with your manufacturer's website to be sure. I'll bet adding Ca/Mg first is universal though.

Unless I had a RO system installed, I don't even know where to get RO water. However, I ignorantly believe that using distilled water is just fine.
I've luckily been adding my Cal Mag 1st followed by FF nutes. There's a lot more luck in my 1st grow, I believe.
FWIW, I add in my nutes, then check pH next day. Make adjustments, if needed.

 

[iwltfum]

re: Shelf life of H2O & nutrients

Most nutrient manufacturers generally recommend speifically to not let nutrient soultions sit stagnant. This is because if the nutrient soultion is left stagnant the molecules have a chance to settle, concentrate, and then mingle. If any heavy molecules bond together at the bottom of a container they will essentially be rendered useless until the medium gets flushed or the resovoir water replaced, which will cause extra -pH changing molecules- to be in your nutrient solution, which could get stuck in the medium, which could throw off your pH until you flush the medium.

Without getting too much into the chemistry of it - or getting into the bacterial and algae possibilities that can happen with an imballanced or settled container of nutrients, which can also throw off pH's or bond to nutrients rendering them either too big for the plants to consume or unrecognizable to the plants at all - that's a very basic explanation on why it's best to not use old stagnant nutrient solution.

 

[growsomebud]

re: Shelf life of H2O & nutrients

Most nutrient manufacturers generally recommend speifically to not let nutrient soultions sit stagnant. This is because if the nutrient soultion is left stagnant the molecules have a chance to settle, concentrate, and then mingle. If any heavy molecules bond together at the bottom of a container they will essentially be rendered useless until the medium gets flushed or the resovoir water replaced, which will cause extra -pH changing molecules- to be in your nutrient solution, which could get stuck in the medium, which could throw off your pH until you flush the medium.


Without getting too much into the chemistry of it - or getting into the bacterial and algae possibilities that can happen with an imballanced or settled container of nutrients, which can also throw off pH's or bond to nutrients rendering them either too big for the plants to consume or unrecognizable to the plants at all - that's a very basic explanation on why it's best to not use old stagnant nutrient solution.

This was my belief. Not for scientific reasons, mind you. I just figured, after making a solution w/ organic ingredients involved, that your solution, after a period of time, can become rancid for lack of a better word.

 

[Scientific]

re: Shelf life of H2O & nutrients

This was my belief. Not for scientific reasons, mind you. I just figured, after making a solution w/ organic ingredients involved, that your solution, after a period of time, can become rancid for lack of a better word.

There aren't any organic ingredients involved. If you look at the label, it's all phosphates, carbonates, nitrates, etc. They can't and don't go "rancid," happily.

 

[Scientific]

re: Shelf life of H2O & nutrients

Most nutrient manufacturers generally recommend speifically to not let nutrient soultions sit stagnant.

With respect, can you provide a link to a manufacturer's site that says that? They do say not to premix the concentrated solutions undiluted right from the bottles, but I have never seen anything about the diluted stock.

If any heavy molecules bond together at the bottom of a container they will essentially be rendered useless

The dissolved mineral salts will be ions in solution and should remain so as far as I can see. Again, I'd be happy to be proven wrong, but this is some pretty simple chemistry.

or getting into the bacterial and algae possibilities

If the solution is kept cool and in the dark, as I said, biology shouldn't be a factor, at least not in the time span of a 12-week grow.

I'm sorry, I don't mean to be argumentative, but I really just can't see any good reason not to premix a week or two's worth of fertilizer in advance. I can't see any advantage whatsoever to mix on day of use. I always mix a week's worth of nutes in advance.

 

[iwltfum]

re: Shelf life of H2O & nutrients

Scientific, I looked in a hydrofarm catalogue at the feed schedule section. You're right that they don't specify on the drain to waste schedules, but they do specify on the recirculating schedules to keep the solution aerated. So I had to assume that if the solution was to sit for a long period of time it was recomended to be aerated.

In terms of the ions not bonding, while they may not bond to eachother when diluted, the minerals will cetainly form bonds if they are all concentrated together at the bottom of a container. It would be a similar situation if you measured out your nutrients from a three part program all into a bucket at once without stiring the water inbetween additions. The concentration of the nutrients causes rapid pH change and changes the structure of the molecules allowing them to bond with each other, and they are very strong bonds when they form like that.

Even in a perfectly areated and pH balanced nutrient solution the water will still encounter bacteria and algae growth if you don't use some kind of sterilization agent, but in a settled solution, those biologicals can more easily find a strata of the water where they can thrive.

I actually very much appreciate the speculation. I think we need it more on this site. And I welcome any more dispute you have on the topic. This is all loosely based on my extensive reading about nutrients when I was experimenting with making my own concentrates and through my dicussions with a company in Idaho when they were formulating their first hydro nutrient line.

 

[Autoflower420]

re: Shelf life of H2O & nutrients

RO water should be cheaper than distilled because it doesn't have to be boiled.

With all due respect to the previous posters, I personally don't see any reason why the mixed ingredients shouldn't last indefinitely if kept sealed in a cool, dark place. It's just mineral salts in solution, after all--liquid fertilizer.

The one important thing is to mix nutes in the correct order. General Hydroponics recommends adding Calcium/Magnesium first. I think that's because it's an alkaline solution and the rest are acidic. In the GH world, you add micro nutrients next, then the rest in any order. Check with your manufacturer's website to be sure. I'll bet adding Ca/Mg first is universal though.

Most feeds sat use within 24 hours

 

[Scientific]

re: Shelf life of H2O & nutrients

they do specify on the recirculating schedules to keep the solution aerated.

That's for oxygen for the roots and to keep undesirable bacteria and algae that like stagnant water from getting a toehold. (I keep a pump or two going as well.) Aeration is not necessary in a sealed storage container.

 

[Scientific]

re: Shelf life of H2O & nutrients

Most feeds sat use within 24 hours

With respect, so you have a link to a manufacturer's website that says that?

 

[Autoflower420]

re: Shelf life of H2O & nutrients

With respect, so you have a link to a manufacturer's website that says that?

Yes gave me 5 mins

 

[Autoflower420]

re: Shelf life of H2O & nutrients

First bottle from my feeds checking rest now

 

[Scientific]

re: Shelf life of H2O & nutrients

First bottle from my feeds checking rest now

Well there it is. Is that a typical NPK fertilizer? That's what I was talking about. (Not molasses/sugary bud conditioners and all that ester stuff.)

 

[iwltfum]

re: Shelf life of H2O & nutrients

Looks like superthrive which is a .5-0-0 but it contains alot of the same ingedients as your average micro nutrient bottle would.