I posted this in another thread as a comment and thought it might be helpful as a topic so here goes…
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Adjusting pH after nutrients are added works if done slowly but there is quite a risk of “unwanted chemistry” and pH swings. My view is that building a neutral, buffered solution before adding nutrients will give you more consistent results. I’m not arguing against pH adjusting after adding nutrients rather suggesting a way to avoid the risk upfront by building a stable “charge-environment” in your water to buffer the affect of added nutrients on pH.
Suggestion for buffering RO or tap water BEFORE adding nutrients.
1.Bring pH up to 11-12
2.Then down to pH 2-3
3.Then back to your desired starting pH (7.0?)
Boom, you now have buffered water which will resist pH swings and unwanted chemistry.
A tip on doing this very inexpensively is to buy reagents from commercial suppliers. Any concentrated base or acid will do as long as you are prepared to handle or learn how to handle liquids that are very caustic. Read an MSDS sheet, get the right gloves and eye protection and have a plan for spills… all can be found online.
Here’s what I use to build a buffer from tap or RO water…
To increase pH
Potassium Hydroxide 50%… ~$50/gallon
To decrease pH
Phosphoric Acid 85%… ~$20/Gallon. 1 drop at this strength will decrease 20-25 gallons of water by 0.1 pH so a gallon goes an incredibly long way vs buying “pH down” from a supplier.
Here are a couple links to show the products but please check the web to get the best deal… I have not done business with these companies etc. Just thought it would be helpful to show a pic and example for those less chemically inclined.
Phosphoric Acid 85% Link
https://www.dudadiesel.com/choose_item.php?id=FGphosg
Potassium Hydroxide 50% Link
https://www.eraqc.com/Products/catalogid/1-4GR6WY/categoryid/1-4GU6MU/catalognumber/183104
Another suggestion from the trench is to get bottles with drip-proof lips. It helps with avoiding a drip of some strong reagent on the table/floor or the side of the container. It’s worth whatever you would have to pay extra if you can get it… most already come with a drip-proof lip but it’s worth checking before buying.
Lastly, I am compelled to suggest one more tip. When adding reagents at these concentrations it is always best to create a more dilute solution to work with. It’s as simple as adding the amount you anticipate using to create the buffer into 1-2 gallons of water and work with the dilute solution. This is safer and easier to hit a desired pH level without “blowing” by it.
Simplified chemistry of this buffer building if you’re interested…
The acid provides a bunch of H+'s
The base provides a bunch of OH-'s
H+'s plus OH-'s = 2 hydrogens plus 1 oxygen or H2O. If there are more Hydrogens in the water this decreases the potential Hydrogen or pH. If there are more OH-'s then the pH goes up.
Easy, so, why does this help keep your pH in line or keep your nutrients from chelating or precipitating out of solution?
Simply put, the addition of all those +'s and -'s is increasing the ability of the solution to neutralize small amounts of added acid or base (AKA your nutrients), ergo maintaining the pH of your nutrient solution relatively stable. All your nutrients in their dissolved state have +'s and -'s so if they are added to a solution with very few +'s or -'s they will have a bigger effect. Picture it in your mind like this… it’s easy to affect the mood in a room of 5 people but if there are 500 much tougher. Try cheering up the mood at a 500 person funeral or bumming people out at a big celebration… If you’re alone you won’t have much effect with your energy (+ or -) in a room of 500 people. Hope that makes a little sense.
If anyone has a better or different way of explaining buffers or perhaps a good, trusted source for these reagents tap it out. I love to learn more about things I can use.
Cheers All !