using a ph meter ?

when using a ph meter on a flood and drain grow would i first take a reading in the nutrient water that i'm about to water the plants with. and the second reading from the run off? i tried using one during my first grow but i never thought i was using it right.

well when you say flood and drain that typically refers to a type of hydroponics system, but then you mention runoff which is used in soil/soiless. so my first question is what medium are you using?

i normally try to take a sample from the overflow hole, the result is similar to taking from the res provided that you are flooding regularly several times a day

I am mostly a soil grower but that being said I think people tend to pay way too much attention to the pH of their run off. Make sure your pH is in the sweet spot for your style of growing no matter if it is soil or hydro and forget about the run off pH unless you have problems and need to troubleshoot. Jmo.

well in htdro its important to travel the spectrum because some nutrients are only taken up in certain ph levels where as in soil the microbes are the ones delegating ph levels at the roots directly. i try to make sure im swinging from 5.5 to 6.3 in pure hydro

Gooch said:

well in hydro its important to travel the spectrum because some nutrients are only taken up in certain ph levels where as in soil the microbes are the ones delegating ph levels at the roots directly. I try to make sure I'm swinging from 5.5 to 6.3 in pure hydro

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Yeah, when I occasionally go Hydro I always start on the low end and let it slowly rise through the spectrum till it gets to the high end. I still have never worried about runoff. Whether in Hydro or Soil. That being said I have never run anything other than DWC buckets. So actual runoff is not existent in Hydro for me.

I agree with Hammy with waiting until you have issues showing up. Unless you just want to do it for understanding better the chemistry that goes on. If you are using hydro, you will have constant change in the solution because of the chemicals that get removed by the plants with each watering/feeding that happens, change the chemical balance that gives the pH. Also, the aeration has a chemical effect as well because you are dissolving chems from the air into the water.

If you are using a reservoir that feeds the flood and drain system, and the solution runoff goes right back into the reservoir(aka rez) then you only need to check the rez every couple days (once you get used to doing it). If it is a new thing then you should check it everyday until you get used to seeing how it reacts and changes over several days. But once you get that understanding of what to expect, you will check it less and less until you have established a schedule.

You don't necessarily want to adjust the pH every day to keep it close to 5.8, you want to let it drift from one end of the allowable spectrum to the other. This spectrum of pH will be different for some strains and certain nutrient brands. For me, using AN's Jungle Juice, I have to set my pH at 6.0-6.2 and allow it to drift down as the plants take in the nutrients. When it reaches 4.5-4.1 I will adjust it back up to 6.0-6.2. Some systems/nutrient brands/plant strains will not like that I go so far down. I allow it in my system because I am used to how my system/nutrients/strains react. I also don't allow the pH to sit very low or very high for more than a day before readjusting. I would say the best rule of thumb is to stay within the 5.2-6.0 range of drift.