First time lowering the PH in rainwater big mistake Just one drop of Ph down and it will take it from 7.2 to 4.5 I have learned Do not add Ph down to rainwater!
@PeeWee66 you cannot pH something that is unstable. You need about 200 ppms in your water before you can get a good reading. I believe rain water is just considered neutral, same as distilled or spring water I believe
No you do not add pH down until you add your nutrients because it will not work. If you’re using plane rainwater without nutrients then I believe it is fine to just water as it is as long as there’s not much ppms
You’ll need to introduce some bicarbonates into your water. Cal mag at 200 ppm will do it and then mix your nutes and check ph.
Also, pH Down is way overrated. I use rainwater. The last thing you do is check the pH and EC or PPM, whichever you are using. Then you add water to lower the EC and then you deal with the pH. I used vinegar instead if pH Down. A single drop of pH Down Into a 27gal container will lower the pH 3 or 4 points. With vinegar I generally will start with a few drops, stir real good and wait a few minutes and retest, however, it is very rare that I need to lower the pH, 99% of the time pH Up is what you should be needing.
Have to be very careful with vinegar I have seen it torch grows. I use citric acid for pH down and baking soda to pH up. Baking soda is basically pure sodium so you have to be aware of that. I used organic apple cider vinegar in a desperate pinch but was very aware of what I was doing.always pH and ppm what water you are using just so you have a basic idea of a starting point. But yes I agree add nutes before manipulating the pH.
Except that it rarely is, if ever. Both water vapor and airborne droplets physically and chemically attach or bond to all sorts of other atmospheric stuff - dust, pollen, particulate and chemical pollutants, etc. - thus affecting its pH and EC. Like acid rain. Ditto for spring water, which absorbs minerals (and pollutants) from its environment.
What Jay was trying to say is just like ro or distilled YOU have to add something to it to get a high enough ppm to be able to adjust the pH.
I agree with you which is why even doing a 27gal tub I would start with a few drops. But also, I think once he starts mixing his nutes in first he won’t have a need to up the pH at all. I think I have used it twice in 4 grows.
Before my old meter got dropped I used an EC reading instead of PPM and even with that black roof powder ick in the bottom the EC was zero 100% of the time. Testing the PPM now and it is most generally down near 100. That’s just my rain water though. I’m sure that different areas, cities, etc, would have different results. Mine is just very clean. I have to more than double the amount of water I start with once I add my Nutes to get the PPM down to an acceptable level.