Overwatered vs Drain

10% runoff should not cause any issues. HEck, due to irrigation setup and some plants drinking faster than others, i regulary get significantly more runoff than 10% and never see droop. droop after irrigation is caused by a poorly constituted substrate. add more perlite or similar next time. "overwatering" means a lot of different things... if oyu are seeing nutrinet symptoms, consult a leaft chart and adjust formual as it is not caused by overwatering. An unhealthy rootzone may cause some funky damage aroudn veins that don't match up well with other leaf symptoms, this could be overwatering. it's a word that gets overused and used wrong often. so it may not be what you are experiencing. simple watering procedure... Since you are using "mineral" nutes i'm going to assume this is a soilless context. 1) fertigate every time with 10% runoff or more. 2) wait for proper dryback and repeat. high water capacity substrate - 50% perlite and wiat for top 1/2 to 1" to dry before repeating something like coco that holds a lot less water only needs ~33% perlite and you repeat once the top starts to change color. if you are choosing the volume of water to give as opposed to giving enough to accomplish the task, stop doing that. 10% runoff is essential to soilless growing. It maintains an equilibrium of nutrients around the roots. If you see symptoms, you need to adjust the formual as you are not providing a well-balanced diet - even if folliwng instructions, lol.... the plant dictates what it wants not some poorly made one-size fits all marijuana branded company's uneducated thoughts on the subject. vege - N 120-130 P 40-60 K 180ish Ca 100+ Mg 75ish Ca 100+ YMMV a bit on these. it's a low PPM starting point with good ratios that don't lock shit out. your local vpd and other variable will impact exact concentration you ant to give. Also, your local tap will contain varying amounts of Mg, Ca, and even N. Think S too? So, some minor adjustments will be needed before you find a formula that works for 95-99% of plants and even those 1-5% that aren't nearly perfect don't will be relatively fine, too. watering and fertilizing are some of the easiest things you will do... keep it simple. Let the plant dictate not any preconceived notions or feelings, and you will do fine. Learn along the way...

Yep wait, I'm in 12L pots and water 5L every 3 or 4 days when the soil has dried a lot.

Make sure to let the soil get really dry thw plant will bounce back for a time then after spil is dry fir a but then plant with start to wilt when you see begging signs of it getting stress from lack of water then water it at that time. A plant will take 3 hrs to recover from lack of water after watering but an over watered plant can take weeks to recover if you keep

If you're showing signs of overwatering it's not about giving less water at a time, it's allowing more time in-between waterings for proper dry back.

Can you upload some photos of this?? maybe it is not what you think it is. With feeding liquid nutrients its always good to get some runoff to prevent buildup. However you can do a scheduled flush ever 2-3 weeks. but its easier to do it every feed. If it is indeed showing signs of overwatering then next time your preparing your medium you need to mix in more perlite so it can not get waterlogged. Also its good idea to water slowly and not all at once as to much water can compact the substrate and cause this problem as well.