How does a RDWC work with beneficial bacteria?

[Neural]

Hello,
I’d like to have more information, if it’s possibile, on how does a rdwc works with beneficial bacteria. How does top-up works? Do I need to change the reservoir once in every few days/weeks? And if so, do I lose all my bennies?

Also, my nutrient solution is never drained fully, shall I just top up? TDS isn’t lowering much, just cause I’m adding RO water, but plants are growing fast and HUGE.

 

[diabolito]

Hey Neural

I may go against the grain on this one, but I tend to only fully change the water at most, a few times in the grow.

Definitely at flip to flower and sometimes during the flower. Otherwise I monitor the PPMs and the Ph and top up accordingly, to get the PPM level I want.

Downside is that it could be possible to be deficient in some nutrients as maybe specific ones are left in the water contributing to PPM and building up. I haven't found this to be the case though and, if anything, sometimes I wish the RDWC growth would slow down a bit compared to my Soil grows. I also try to randomly vary the PH within the 5.5-6.0 range during a grow as certain PH levels favours different nutrients.

My reasoning is that the Nutes are expensive and it doesn't make sense to be throwing it out every few days. Also the plants start to consume a lot of water once they start growing, so a large portion of water is being swapped out anyway.

 

[LKABudMan]

I'm on my second grow with my RDWC system (50gal total res). On the first grow, I kept the same res all the way through flower, adding nutrients or plain water as the plants/ppm/ph dictated. This time, I plan on changing the res twice: Start of flower, and week 6 of flower. This allows me to reset the res at specific points in the grow, and to make sure I know what's in the res coming into the end of flower. For the rest of the time, I'll just top off my res. Here's my grow tracker from my last grow. You can see how I top off with nutes a lot early, and mostly water late. I top off bennies regularly to keep anything else from growing in there.

Screenshot_20220620-121035_Sheets.jpg

• LKABudMan
• Jun 20, 2022

3rd grow tracker RDWC final

 

[Rexer]

The rules of thumb to not worry:

Change the res every 7-10 days. Truthfully though, You can really ignore that in veg near the start.

But when your reservoir depletes 60-70% of the initial PPM, swap it out. Dump and reset. Especially in flower. But that's my opinion.
Your plants feed based on ratios (to simplify it). They don't always feed at the same rate, and the little bits of leftovers overtime has an impact on the ratios. That's why you reset/dump.

Depending on what beneficials you're using, that dictates how often they need to be re-added to keep the microbe herd going strong. It should say right on the bottle.


I should add: we all find what works for us and makes us happy as far as what works.
The differences in methods discussed above shows that. The more you grow, the more you'll find what works for you and your setup.