the question is, in hydro system, if i have a clean system, with no “contaminants”, i still need change the water periodacally ?
I cant just add the fertilizers and CaliMaGic … ?
What the water loose with the time that make us to change to a new one ?
i’m planning a quiclky travel, 10 days, and i already have everything working automated, unless the water change. For how long i can use the same water, just adding fert and regulating the PH ?
Some of our member NEVER change out the solution.
Personally I change mine once I flip to flower and as they drink I just top it back up with water then add nutrients to raise the ppm to the level I need.
Running 4 sites and reservoir I have 35 gallons in play.
If everything is stable I just top up keeping my ppm and ph in check.
I dump at flower and then again at 30 just to make sure I’m not caring too much N from transition.
Enjoy
I use it for houseplants in the winter, and use it outside in my garden if spring/summer/fall but wouldn’t use it for other hydro. To much hassle to get it right again but usually fine for the other plants if in soil as a buffer. 
My 4 site with exterior res uses 81-120L depending so I wanted to save on nutes as well but found that every 2 weeks is the sweet spot for me to have a total res change. 3 weeks depending on when in the cycle can work but when i’ve had problems it’s ALWAYS near the 3 week mark.
Best of successes!
I’m not a hydro guy so I don’t know how this works.
Do you do a math guess? I need to top up 5g in a 30g Rez so I need pH X and ppm X to balance it out?
Curious how this is done.
4 grows same rez for me
I add water when needed and nutrients if the ppm drops
No maths. I use my e.c meter to get it back to the level the plants were happiest.
Top up with water
Add nutrients a bit at a time till I hit my ppm requirement.
Adjust pH by adding a few drops of up/down at a time till in range.
Jobs done.
My f*ck ups in my grows usually come down to my laziness not cleaning and reconfiguring my pH meter as often as I really should.
Yes that makes more sense. Thanks.
No maths. I use my e.c meter to get it back to the level the plants were happiest.
same here… my only question is if i need change this solution to a new, or i just can add water to make the water level and adjust the ppm with proportional fertilizer…
if i add 5L of watter, i take the GH chart, divide 5 / 3.8 = 1,315 then multiply this for the “recomended ml for a gallon”.
Great notice… i will travel more quiet :
and waste less fertilizer and water 
…
Yep.
My choice to change the res every 2 weeks is so i don’t need to keep adding as I go.
Every AM check PPM/EC/PH, Every PM the same and topped off as often as required with water that’s been PH adjusted to match.
in my first and second week, i still have some points of light infiltration and my water isnt being well oxigenated… so the water started smelling bad.
but now, 4 weeks of growing, the water quality is stable… i will make the test and just add new water but not throwing the older out
I put panda film over my totes to block light
Also I use hydroguard
That’s the “correct” way to do it bro. The levels of each element in the nutrient used by the plants change as they grow. A plant maybe using more nitrogen than any other element so that will be dropping more than the rest so topping it off just adds more of say phosphorus that isnt being used as much that in the end can build up and cause toxicity.
I’m gonna dump my rez and reset tomorrow now FFS 
Each of my buckets are 30 litres. Entire system is 150l so not that big really. I’d change it out more often if it wasn’t a PITA.
My logic: It’s better to “waste” 2 weeks of nutes than get a lockout and “FUCK UP” an entire cycle.
@Hydro921 , the bigger the system the more forgiving… but when it goes back it’s ROYAL 
Yeah I’m the king of lockouts but it always ends up being my pH. Cleaning and reconfiguring my meter is one of them jobs I’m always doing tomorrow 
USA gallon is different to ours
The gallon is the only thing that’s NOT bigger in America lol
Reviving an old post, was thinking of how I do this and wanted to add my 2 cents.
I tend to rez change at 12/12 transition like many here. Generally just to have a clean slate and bump my EC. I dont change nute formulation- Jack’s 321 straight through.
After that’s it depends how busy I am.
I target an EC of ~1.4 in flower.
If everything is going well then I can just top up.
Going well is, water level is dropping & ph is stable or rising slightly while ec is stable.
If my EC rises significantly, say to 1.6 or 1.7 I know the plant is taking up water faster than nutrients, and likely I am getting a build up of something.
I’ll generally top back up with water to bring it back in line. If I notice it again, it’s a rez change.
Also generally fall back to, when in doubt dump it out. If things look off in the grow its change out time.
