Super Interesting behavior in RDWC

So I got a 20 bucket RDWC system setup and i am in week 6 of flower.
I do a water change every 7 days.
Wtemp is 70 and i feed them lucas 8ml/16ml + Liquid KoolBloom + Floralicious PLus ppm is about 1190 / 500scale and 180ppm tap water
I have an auto top off setup with a 3 stage water filter.

Now this is where it gets interesting. I have grown like this a few times and almost always the ppm starts at say 1190 and gradually declines until about the 4th day that i add back some nuts or just wait till the 7th day and do a water change.
But recently ( the last 4 weeks ) I start off with say 1190 ppm and next day ppm is down to 900 ( they consumed 290ppm ) but after that 1st initial day they consume like 50 ppm then 20 ppm and basically they stop eating by the 4th day.
I would love to get some insight from you guys on what is going on. Why do they eat some much the 1st day of water change then quickly decline the following few days?

Here is a photo of my ppm / ph chart / green is when i do a water change !

Good question I been growing RDWC for last 2 years same thing happens to me. Not sure why but I believe with the fresh nutes they have even levels of everything. As they take certain elements out the water once they get the man nutrients they need kinda slow down. Plants look green and healthy yields are amazing so I would not sweat it. Also depends how much water they are drinking cause if they drinking a lot water they still eating. When your ec in that sweet spot your ppm kinda stay the same you won’t see big decline but a lot water still being consumed so you have to add more nutes to keep the ppm’s up.

Jdubb203 said:

Good question I been growing RDWC for last 2 years same thing happens to me. Not sure why but I believe with the fresh nutes they have even levels of everything. As they take certain elements out the water once they get the man nutrients they need kinda slow down. Plants look green and healthy yields are amazing so I would not sweat it. Also depends how much water they are drinking cause if they drinking a lot water they still eating. When your ec in that sweet spot your ppm kinda stay the same you won’t see big decline but a lot water still being consumed so you have to add more nutes to keep the ppm’s up.

Click to expand...

Im not complaining that they are eating like beasts but would love to find out why they eat so much the 1st day then sharp decline after that. from my photo which showed the last ppm of 870 and today it was down to 820 aka 50 ppm , so they went from eating 190ppm the 1st day down to only 50 the 3rd day.
Also since my top off is just 3 stage water with a ppm of about 180 does that mean they are eating more then 50 say and the top off is increasing the ppm ? or is the baseline 180 ? having a hard time figuring this out honestly.
Oh and important Note* i have tip burns so i know the ppm is too high so if ppm is too high then why do they eat so much lol .
So many question so little weeks left to figure out lol

You only got couple weeks left to solve the mystery lol

I want to ask the community if anyone else is growing with 3 stage filter and having success? I can only think that the water quality is the issue