Exit EC in peat and perlite

The limited number of characters when asking a question made it difficult to formulate something that made sense. Can't quite nail down the whole water to run-off or not when in peat & perlite (ProMix HP). Opinions seem all over the map with no clear majority to guide a newbie. Given that - if no run-off consistently - is the accepted majority opinion Can a grower in this substrate style actually learn anything meaningful with an EC substrate probe. Struggling to see the value of a pen to measure liquid in and probe to measure substrate after - since using 2 devices likely won't give readings you can compare or trust.

Am using Bluelab is perfect get the care package and can last for years

Yes the probes work to answer your question. I would stay away from the cheapest ones as you get what you pay for.

with a soilless substrate you fertilize every single time iwth a relative mild 1.3-1.5EC concentration of well-balanced NPKCaMgS + trace elements. Any reputable soilles/hydro nute will be 100% chelated, 100% soluble, and ready for plant intake immediately. It should also be pH buffered, otherwise you have to deal with potential pH drift. A headache that should never really happen with well-made hydro/soilles fertilizer. runoff will always be different. it's important to have a baseline before you react to it... so if the plant is healthy, keep checking, but don't react unless plant starts to show symptoms potentially related to whatever you see. if it's 100% healthy for months, you can assume any deviation in runoff is normal and that is the baseline from which you will compare in future, not what you added. tap water adds to that suggest EC above. So, that alone makes it higher. But runoff is mostly the remnants of previoust fertigation + evaporation that occured. it's 'flushed' out, so your runoff will be higher. now, your drain basin may have dried up nutes, this too will raise the EC reading. When you measure it - early or late in runoff - will affect the measurement. So, you see this measurement is neither precise nor accurate. That doesn't mean it is not useful, but just don't judge it based on what you are adding, because it's not that. the 10% runoff will ensure no buildup occurs. if religious about this, pH is relatively steady and you start to see symptoms in leaves you can be certain it is the fertilizer formula and not buildup from fertigation habits. This makes diagnosing easy and eliminates much of the need to test runoff... spot checking is great. if you use good hydro nutes, it is absolutely not necessary to do it often. pH is important. I rarely test it. I use 100 test strips in 5 years or more. Do it at specific moments to ensure your tap water hasn't shifted pH -- which again, ph-buffered nutes will mitigate this with no problem - but we don't always give fertilzied water. e.g. the first irrigation or 2 for a seedling may not have any nutes at all. This would not be pH buffered out of the tap or RO or whatever source you have for water, so testing it would be more important. ph buffering is different than ph balancing. with good fertilizer, you won't have to ph-balance at all. spot check occasionally when you are at risk - mostly a seedlings / clones context when ph-buffered fertilizer is less likely used. check out my google drive link in my profile. the shared folder has some charts for reference that are useful and a nutrient spreadsheet that has instruction in cell 1 -- you can download it but you cannot edit it on google for obvious reasons, since i share it publicly. leaf symptom chart are also very useful to keep handy mulder's chart my suggestion work out a formula that gives you : PPM / Nute 120-130N 50+ P 180+ K 100+ Ca 50+ Mg less than 110 S ca/mg will vary by water you use. some will need more, some less. the rest should be fairly consistent. and all of that at ~6pH give or take a couple tenths. different pH may shift these a bit, too. between pH's effect and mulder's chart, this is complicated stuff trying to hone a proper recipe. this is based on research of larger Ag companies. from what i understand it mimics some of the most fertile land on earth. you can find this resulting ratio in Souther Ag, Jacks 3-2-1, Masterblend, and floraflex pro line of dry nutes among others... it's non accident thay all use roughly the same ratio ofnutes in their formulas. it's based on the same research. in my experience, i have vno issues with running several strains off of one reservoir. occasionally a strain wants more or less N. In bloom yo may need to drop N 5-10% but nothing drastic. simply watch leaves and if they get too dark, ease back. the above ppms will be below 1.3EC, i believe, so there is room to add some here and there based on plant observation. always easy to add than take away... keep track. see what works long-term. just because it looks healthy the first week after you adjust the formula, doesn't mean all is fine. With small descrepancies, it takes a very long time for symptoms to form. This is a good thing and you'llknow to only make a small adustment in future to fix it, but may need to make a slightly larger reaction in the moment to counteract what happened over that time. the next run you can avoid it.