So when you say you’re using 125 or 150% of Jacks do you mean you’re increasing the 321 to be a little heavy?? Does that work well or do you end up burning the ladies? If so how long do you run them like that? Sorry if it’s readily available and I just missed it.
Hey there,
Yes. Running a bit heavy. So normal Jacks 100% formula is for photoperiods. I back off to 60-80% for autos. I collect my runoff in coco and test the EC/ppm. If it's below input I increase the strength until it starts to stay at or above input. I try to keep the runoff PPM below 300 over input. Ex: I put in 1000ppm, runoff needs to stay below 1300. If it's over, then either reduce strength or increase volume for more runoff. I have not had any burn issues as long as it is kept within range. Some plants are more picky so you will need to watch and see if they like full strength or 80% or less.
I did get a week where I was out of town and put them on a reservoir and pump setup. The runoff ppms climbed to over 2000 and it took a lot of flushing to get it back in range. They did suffer some tip burn from it. Fortunately it was a brief episode and they don't really look worse for wear.
These were the first plants I've grown that wanted more than the regular full strength. Beasty, hungry, monsters. The Devils Lettuce in particular was very happy at about 1200ppm of input. When I pushed the 150% for a feed or two the runoff climbed so I dropped back down.
I mix 4 gallons at a time so increases are easy. I put one "dose" per gallon for 100% mix, at 125% I simply multiply by 5 and so on.
100% in grams per gallon - 3.6g part A : 1.3g Epsom : 2.4g Part B
4 gallons at 100%: 14.4g A : 5.2g E : 9.6g B
125% - 18g A : 6.5g E : 12g B
150% - 21.6g A : 7.8g E : 14.4g B
How long do I run it? These were photos so Flowering was easy, flip the lights and adjust the nute blend.
Once in flowering I do adjust and use the Jacks "Finish" product. I blend it in week by week reducing the "regular" formula and increasing the "Finish." Again, just watch the runoff ppm and adjust as needed. They are currently on 1 Part regular and 3 parts Finish which comes out at ~820-865ppm.
I do use RO water to start which is 0 ppm. I add usually 20-25ppm of a silica product. This brings the pH up and holds it very steady. The Jacks tends to run low pH on it's own. Silica is a good addition anyways and the pH buffer is perfect. Test and tune the amount and you should be able to hit your pH target without needing pH up or down.
Let me know if you have any other questions. I'm definitely not a pro or as knowledgeable as some of the guys here but I will absolutely help if I can.
Current Auto grow here: 80% strength and same stepped "Finish" schedule just reduced dose.