Been trying to find an answer but end up with nothing so it’s always better to ask here. I have 2 plants in 50 liters interconnected buckets for a total of 100 liters, they are in late flowering (3-4 weeks to go), I use the full range of GHE nutes (micro, bloom, gro, diamond nectar, mineral magic, gh bloom and gh roots), with ro water. They are drinking around 15 liters combined daily hence I top up every 2 days and complete change every week. For some reason pH keeps crashing and I add 30ml of pH up daily, but this is not practical apart from money wise I cannot understand why, any help or any question I need to answer please let me know as I am going insane. I have a time lapse video of the last 24 hours but I cannot upload it 
basically at night everything was fine up until the last 8 hours where pH crashed from 5.6 to 4.6
What are the ppm’s/tds in your system?
Are you going by the GH schedule on their website?
In what order do you mix your nutes?
How are the roots looking?
What’s the water temp?
Plenty of room between netpot and water?
Just a little FYI, Jack’s 321 might be a little economically friendly next grow.
I don’t grow hydro, but it seems like your pH could fluctuate with your TDS. Especially in RO. Your nutrients are basically holding the pH because there are no other dissolved solids. If your PPM drops you have less buffer.
At least that reasoning tracks in my brain. But like I said, I don’t grow hydro.
So my ec is fluctuant between 1.3-1.6 (I use pH guardian)
Yes gh schedule but I always lower it down with nutes as I believe the plant doesn’t need that much
micro, gro, bloom, gh bloom (concentrated), silicate powder
roots are great
18c is the temp constantly
around half inch between netpot and water
I actually add 2-4 liters of tap water to it, which seemed to help slightly
Should be 1 1/2 - 2 in gap between bottom of net pot and water. And the top of the water should look like a full rolling boil from the air stones.
Thinking this may also be contributing to the droopy leaves.
Let me tag a couple hydro guys.
@Myfriendis410. @peachfuzz.
Could you fellas lend some assistance ?
@Laqwanies. They’ll be able to steer you straight.
This is the problem with smaller standing reservoirs: PH tends to fluctuate. Especially later in the life cycle. Yeah; drop your level down to 1 1/2" to avoid damping off the main stem.
If you have silica you can use that instead of PH up to raise PH: you have to pre mix into a smaller container then add to main solution until PH is in your target range.
What is considered as large reservoir? These tank hold 100 liters combined. I remember when I started I used to have a 20 liter bucket damn haha.
This is the height I keep water from net pot.
I have silicate I use it through out all the cycle, and I also dissolve it in a separate container prior in putting it in but it always keeps sediment at the bottom, it never dissolves completely.
Thanks mate <3
Another 100 liters tied into the system would help to keep PH in line.
Are the tubs just connected without water flow from a water pump ?
By simply having water movement it makes the solution more stable and easier to keep maintained.
A simple solution since you have a chiller would be an intake to chiller from one pail and the output from chiller to the other pail at farthest points from each other. Of corse this is if you dont have water flow set up already.
It’s actually quite hard to diagnose a system with limited information. So many variables
Water pump creates enough water flow and as far as I remember roots don’t like movement very much unless I’m mistaken.
That’s how it’s setup, water is pumped from one tank, through the chiller and out the other.
That’s why I asked for any questions anyone can ask me and I’ll reply.
Apparently the issue was nutes imbalance, after a couple of days when they drink enough water and I top it up it kept stable for 4 days until I changed the water, then it started fluctuating daily. Trying constantly to change the nutes I add until I find the sweet spot for this stage.