yoshisisland
Member
how often does everyone change there res on a rdwc? anyone had success without doing a change?
how often do you change your res before flower?
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PetFlora
Well-Known Member
excellent question
When starting seedlings or clones not much nutrient is used, BUT, depending on how you aerate, you might need to adjust pH daily, or at the very least check it daily. This requires moving the lid. That's a PITA, which only gets more difficult once the roots and plants develop. How are you going to lift the entire lid up to check pH and ppm daily?
Not to worry, convert it to a outboard rez, where access is immediate without disturbing the plants or roots. Simple Bulk Head fitting from marine industry + a hole saw. I also buy appropriate O rings to ensure better seal, otherwise it can leak
Now you can dump and replace nutes, check pH and PPM/EC s needed
When starting seedlings or clones not much nutrient is used, BUT, depending on how you aerate, you might need to adjust pH daily, or at the very least check it daily. This requires moving the lid. That's a PITA, which only gets more difficult once the roots and plants develop. How are you going to lift the entire lid up to check pH and ppm daily?
Not to worry, convert it to a outboard rez, where access is immediate without disturbing the plants or roots. Simple Bulk Head fitting from marine industry + a hole saw. I also buy appropriate O rings to ensure better seal, otherwise it can leak
Now you can dump and replace nutes, check pH and PPM/EC s needed
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Lordhooha
Well-Known Member
I change as I switch to flower and maybe in the middle of flower. Beneficial bacteria is your friend if you run your system this way.
yoshisisland
Member
ive been using voodoo juice and havent had any problems yet, im on week 6 of flower and im having trouble keeping my res below 75 think this will be enough?
Airwalker16
Well-Known Member
I’ve never changed water before in my RDWC grows. I do have a chiller keeping my system at 65*-68* though. But they drink SO Much that it’s really a game of just keeping the system full at all.
Lordhooha
Well-Known Member
Install a float valve and set it to top off automatically.
HydroEnthused
Active Member
Once every 7-10 days I’ll change out roughly 13-15 gallons from 36 -20 gal Rubbermaid brute bins for a total water change of approximately 475 gallons. None of the bins are connected with piping. They are all separately topped off with RO water with an improvised automatic system.
It’s much easier to just change all the water in a short (7-10 day) time interval than try to separately adjust pH in 36 separate containers. It’s actually really easy to do the water change because I have an elaborate electrical water changing system (Over 300 Solenoids/motorized ball valves and roughly1,000 ice cube relays) that does it for me! But even if I didn’t have an automatic water changing system it would still be easier to just change all the water instead of trying to adjust the pH because of all the separate containers in my particular case study. I simply start the nute mix between 1.6-1.8 ec @ around 6.3 pH and wait until it dwindles down to 5.5. Whatever is the average length of time to get to 5.5 (longer times in the beginning of flower, shorter times between week 6-10 or beyond) is the best time interval between water change. My 10 yrs of experience in DWC has shown the 7-10 day time interval to work when your tub never goes above 75f, and the canopy height temp reading never goes above 84f (if you have a week 7 or beyond canopy height reading of 84f you should be getting a “just 6” above the res” reading of 76f if your water is 75f all without chillers because your aeration system provides a certain amount of evaporative cooling when properly set-up) and this combo of water change interval and room temp always gets me over 1gpw.
Also, you will need about 18 lpm of aeration through ceramic 8” air stones that only pump clean room/medical grade air (not pure oxygen). If you only pump scrubbed air your pondmaster diaphragms will last about 4 years. Before pumping clean air I could only go 6 months before abysmally diminished air pump performance.That’s the AP-100 Pondmaster diaphragm. Clean room aeration technique is critical because this is the only way that you are not adding dust (sometimes in the form of combustion soot, the worst enemy of air stones and air pump diaphragms) to your nutrient solution.
With those parameters you will have the opportunity to become a DWC cannabis Mr. Guru.
It’s much easier to just change all the water in a short (7-10 day) time interval than try to separately adjust pH in 36 separate containers. It’s actually really easy to do the water change because I have an elaborate electrical water changing system (Over 300 Solenoids/motorized ball valves and roughly1,000 ice cube relays) that does it for me! But even if I didn’t have an automatic water changing system it would still be easier to just change all the water instead of trying to adjust the pH because of all the separate containers in my particular case study. I simply start the nute mix between 1.6-1.8 ec @ around 6.3 pH and wait until it dwindles down to 5.5. Whatever is the average length of time to get to 5.5 (longer times in the beginning of flower, shorter times between week 6-10 or beyond) is the best time interval between water change. My 10 yrs of experience in DWC has shown the 7-10 day time interval to work when your tub never goes above 75f, and the canopy height temp reading never goes above 84f (if you have a week 7 or beyond canopy height reading of 84f you should be getting a “just 6” above the res” reading of 76f if your water is 75f all without chillers because your aeration system provides a certain amount of evaporative cooling when properly set-up) and this combo of water change interval and room temp always gets me over 1gpw.
Also, you will need about 18 lpm of aeration through ceramic 8” air stones that only pump clean room/medical grade air (not pure oxygen). If you only pump scrubbed air your pondmaster diaphragms will last about 4 years. Before pumping clean air I could only go 6 months before abysmally diminished air pump performance.That’s the AP-100 Pondmaster diaphragm. Clean room aeration technique is critical because this is the only way that you are not adding dust (sometimes in the form of combustion soot, the worst enemy of air stones and air pump diaphragms) to your nutrient solution.
With those parameters you will have the opportunity to become a DWC cannabis Mr. Guru.