About the amount of HCL water that needs to be added...

Ron's tek talks about adding 300ml limonene to the cactus, then pour it off, and then add 25ml HCL water. But...
I never get all of the 300ml limonene back, more like 200ml or a bit less even, it varies. So...

My question is: how much HCL water - percentage wise compared to the d-limonene needs to be added?

And just out of curiosity, how is the amount needed determined exactly? I mean is it based on experimenting?... Or does the amount needed have it roots in some calculation based on specific knowledge?

It doesn't matter that much, 100mL isn't too much. It will just take longer to dry and might not be quite as clean, but it will get most all of the goodies out. Also, if you're putting the limo back in for another pull, you would want to use less because you can get the rest out next time. But if you're using fresh limo for another pull, you want to wash the used limo enough to make sure you get everything out.

The HCL wash has a distinctive smell that diminishes with each wash. I generally wash with 50 mL volumes until they come out clean, reducing volumes each time.

Edit, oh btw, I made a typo in my original post, the 100ml HCL water should have been 25ml, so anyway,...

You mean you use 50ml HCL water when you start off with adding 300ml limonene to the cactus mix?

I've been adding 7.5ml to 55ml poured off limonene (which is the same ratio as adding 25ml HCL water to 300ml limonene that still has to be poured off, so eventually it's more like 25ml HCL water and 200ml limonene).

Batch 6 & 7 are drying now, so maybe it's too little HCL water considering I still get goodies out of the limonene. I'm also experimenting with the PH of the HCL water though, so that could also be the cause.

Sorry, I'm just not particular about washing. For a typical 200-300ml of limo, I'll take around 200 mL of dH20 and add 5 drops of 10% HCL. Add 50 mL or so, around 1/3 or less the volume of the limo, in a sep funnel. And then I don't drain all the wash because of the film between the layers. It's more about the method than the ingredients. You do what makes sense for your equipment and the volumes you are working with. If you don't have one already, get a sep funnel.

HCL is nice because the extra will evaporate. If you're washing with fumaric, the volumes are more important so you're not wasting and contaminating.

Hey, I'm just the kind of guy that likes to learn everything when it comes to a subject of ineterest, so nevermind me wanting to know every detail

Anyway, thanks for your input, I'll just go with 25% or so for my next batches. About PH, do you also find that when you add HCL at first the PH lowers pretty quickly, but then the amount you have to add increases significantly? For example, to go from PH 7.5 to lets say 2...it's done with 5-8 drops or something. But then from PH 2 to 1 it takes more like 20-30 drops. Just something I noticed.

PH follows a logarithmic curve, so it definitely takes more and more to get higher or lower at the ends of the scale.