Ive been considering that in the future tbh, I rent so RO isn't really feasible and I use disstilled when making compost teas since i have to buy them by the gallon. I attempted no flushing this round but it just caused build up to the point where i was at +2200ppm(my tap is about 160). It wasn't until I went back in my notes and realized my ph range was too narrow over a few weeks causing the lcokout.
I am using megacrop 2 part for the first time and and have a new environment to grow in so I def had my growing pains this round. Almost at the finish line though
I own my own place but our tap water comes from a dugout on the acreage so we've been buying RO water for over 20 years for drinking and using for my plants. About 2 years ago now I spent 0ver $500 buying special filters, housings and an UV sterilizer so we can make our own RO water. Ups and down with health issues for me and the wife have contributed to not getting it up and running yet. Today I had to run down the highway to a town 20 miles away and took 4 jugs with me as the store in town has gone up to $4.50 each so figured if I have to go further anyways I'll get 4 jugs for $4 each to find they've raised their price to $5 freaking dollars! That is the straw that broke this old camel's back so I'm getting that shit installed ASAP come hell or high water. My feed water is free so after the first 110 jugs the system has paid for itself. We use 2 jugs a week when I'm not growing but can go over 5 when I do so won't take long to hit break even.
When you use tap water at 160ppm most of those mineral salts in that water are left behind as the water level goes down and you add more water which raises the proportion of mineral salts from your water in relation to the mineral salts in your nutes. The general rule when using water like that is to do a complete nute change once you have added back the same amount of water your system holds in total. Same rule whether you are doing DWC in stand alone 5gal pails, RDWC with many pails linked together or like I always used was Rubbermaid tubs. This means that in the early stage when the plants are small you don't need to change nutes for probably the first month or more. You can just add small amounts of nutes to keep your nutrient ppm up and raise it as the plants get bigger and need more.
Because I used basically pure water I never had to deal with added junk mineral salts from the water. At first I only needed to top up the tubs every 10 days but as the plants got bigger, and I'd have 4 or more plants in each tub, I would top up every 3 days. First I'd fill to the level I wanted with water and let it mix for a while while the bubbles from the air stones stirred it up. Then I would test pH, (before I got the pH Perfect nutes), and ppm. Then I knew how much the ppm had dropped and using syringes would guesstimate how much of each of the 3 bottles I had to add back to keep near my target level. Or raise the ppm to a higher target as the plants ppm drop got larger as they got bigger.
Being a tad on the lazy side I was only doing about 3 nute changes for a whole grow. When I was ready to flip to 12/12 I would pre-mix a stronger nutrient batch in a taller tub after vegging in one of the shorter ones. 50L in a tall tub vs 35L in the short ones. I would also be adding more of the Bloom and a half dose of Big Bud then just lift the lid with the plants and drop it on the bigger tub. Give them a week to get used to that then flip while adding the other half of the BB and enough nutes to stay at my target level. Within a week of the flip as the plants got into the stretch period daily ppm drop could increase up to 4X pre-flip levels as they enter a huge growth spurt. Good time to add extra light, add CO2 and allow the room temp to go up to 90F before the exhaust fan kicks in. Very dry air here so humidity was rarely a problem or cause the exhaust fan to run. I have it on a temp/rh controller and also speed control set to half speed. Once stretch is over it was easy to tell as the daily ppm drop would quickly go back to pre-flip levels and gradually become less as flowering went on.
So my 2nd nute change would be after the stretch was over where I'd switch my feed to Lucas Formula type feeding using no Grow and 1 part Micro to 2 parts Bloom. but would use less Calmag and more Epsom salts as the need for calcium, nitrogen and phosphorous goes down later in flower but the need for Mg, potassium and sulphur go up for fattening up the colas and pumping out the resin. The Epsom Salts take care of the Mg and S and I have potassium chloride I would use for extra K. I would have stopped the Big bud at the end of week 5 for a 9 week strain and allow the ppm level to keep dropping by adding less of the Micro and Bloom so within a couple weeks of cropping lower fan leaves would start going yellow and limp as the plants relocated N and any other mobile nutes they needed to feed the buds. My 3rd change would be just a couple weeks before cropping if I bothered with it at all and be only 300ppm of Micro/Bloom and a couple hundred more if Epsom and K.
Then one 2-tub grow of the same strain I tried not changing nutes at all with one tub and it grew just as well as the other so stopped doing changes at all. Hit my lazy bone just right.
I used some of the older 1-part MegaCrop nutes with ProMix HP a few years ago now and the plants did great in veg but after going into flower they started not doing so well a week after the flip and went downhill from there.
I think I'm gonna copy all that to a text file for the next guy and save my fingers some wear and tear. lol
