High Kage87
I've been growing with Promix HP for a number of years now and might have a little insight into your high runoff. HP has dolomitic and calcitic limestone added to counter the low pH inherent in peat moss. Once you first water your plants it begins to dissolve and greatly increases the amount of mineral salts/ppm in the pots. Then you pour in your nutes and test your runoff to find it's way higher than what you added.
Perfectly normal and to be expected. Thing is you don't want any runoff with it using RO water. I go whole grows without ever removing runoff once unless I've miscalculated and gave them too much. Then I'll suck that out with a turkey baster and give it to other plants that sucked up anything that initially ran out after watering. Or save it in a jar and give it back to that plant the next day when it has used up some of it's water.
I let the pots get pretty dry and judge when to water by hoisting the pot up a bit to feel it's weight. I'll also measure the amount of water it takes to totally saturate a dry pot and when I next have to water I can just add 10% less than that and pour the whole amount into the pot and walk away if I want. It will pour thru and fill the catch pan right to the rim sometimes if it's really fry so have to watch it doesn't overflow but I'm getting good at not doing that. I'll let it sit for at least an hour and if it's all gone maybe add a bit more water to make sure it's totally soaked and no dry areas in the root zone. If it still has water in the pan then I suck that out.
I'm not familiar with Remo nutes but sure know that name. I checked them out and they look like pretty good stuff. After mixing what you are going to feed your plants what pH do you get before adjusting?
After all the flushing you've done trying to correct a perceived problem you've likely washed out a lot of the buffering capacity that was there when you started by removing a lot of the dissolved lime. You might want to water with a bit higher pH.
I do DWC as well and check my ppm for that but not with plants I grow in pots. I go by fractions of what it says on the jugs to feed. I use AN 3-part nutes and have for 17 years. They say to use 4ml/L and I consider that max strength so for small plants I'll use 1ml/L in small pots then as they grow and move to larger quarters I'll use 1.5 - 2ml/L every 2nd watering. With vigorous growth and bigger plants I'll go up to 3ml/L but have never in years gone to 4. Easy to burn plants with hydro nutes especially if you have very low humidity like we have here way up in northern Alberta. During the winter months it can be hard to keep the RH over 30% and I may feed half as much to prevent nute burn. Hate those dry, crispy fan leaves about 5 weeks into flowering and it's only been a couple of years that I clued into vapour pressure deficit and it's implications in nutrient uptake and plant growth. Getting a handle on that now.
No end of things to learn growing pot or any plants I guess. Helps keep the oldtimer's disease at bay I hope.