So, I'm knee deep into my first DWC system. I have individual buckets with net pots for the veg room and an Under Current 2 x 6 system for flowering. I'm getting to the tail end of veg and I have to finish building the flower room before I can put that system together. But what I've learned so far...
DWC, whether it RDWC or not - maximizes the plant's nutrient needs pretty perfectly, but there's almost zero margin for error. With these systems, when something goes wrong, which it will, the results can be catastrophic literally within a day. It's a lot like owning a formula 1 race car - sure, you can probably make it go, but it won't go turbo until you really get it dialed in. Soil, and even cocoa or rock wool, gives you much more room to be able to withstand mistakes or environmental extremes.
Chiller - absolutely necessary. Even if you are perfectly diligent with maintaining disinfectant levels, cool water temps will keep bad bugs from growing so fast, giving the disinfectants a better chance to work, and roots at their best. Example - an air pump failure can cause root rot to set in in less than a day. Even if you catch it relatively soon, a thin layer of bacteria will stop root growth entirely until the problem is corrected and new roots grow through. I had a main line from and air pump come partially dislodged for a night, and even just that caused my roots to turn beige instead of bright white. I'm still battling it a week and a half later. I was lucky it didn't come completely off. Another time, a bucket was sitting on an air line for a day and same result. These problems cost time, which costs resources - and $$. These are costs that are hard to calculate.
Yeah, you really want to be changing nutes weekly, unless your roots are perfect and you're confident in the bacteria levels. But for your first grow, I'd err on the side of caution and change it out weekly. A lost 2 weeks of growth due to a problem will cost more that the extra water and nutes. Also, every single change, every single time - clean every single component with bleach. Buckets, air stones... all of it - every week. It's a lot of work with individual buckets - even when they are connected - it all has to be drained and disinfected every time or else you are just re-seeding the new batch of nutes with bacteria. It's also hard to maintain a beneficial bacteria count when you also need to kill off the bad bacteria. Some people can maintain their system with only chillers and beneficials - but it's really taking a risk.
I'm learning as I go, even though I thought I had it all researched. Each lesson costs me time, resources and $ - hopefully I'll keep improving.
A power failure can easily destroy everything. With that water sitting with no chiller or air pump - it's going to die pretty quick.
If you can't afford to lose an entire crop if something fails, don't do it. With so many crucial components, there are so many points of failure.
Oh, another thing to consider... A 6 or 8 pot system is going to be 20+ gallons at a minimum per week. Depending on your water quality, you'll probably want to use RO water. You can buy it at Wal Mart for .88/gal - that's a lot of work to be hauling 25 gallons a week - and expense. A little RO unit will be ~$250 and you can make your own. It puts out a trickle of water, and wastes as much as it makes, but over the course of a day, it can fill your mix tank.
Huge mistake #1... Don't flood your basement - like I did... This little RO comes with a hose adapter to hook up to a sink. I put in a hose adapter onto a faucet, then put a Y adapter with valves and connected the RO to that. My thought was that I could still use the faucet while the RO was connected. I hooked everything up at the end of a night of work, tested the RO, shut it off (so it wouldn't spring a leak in the night) and went to bed. The next day, about 11 am I went downstairs to find water spraying from the sink all the way across the room and about an inch of water covering everything. I had shut the water off at the valve on the Y adapter, and not at the faucet. The hose adapter on the faucet (which was brand new) split. This is a finished basement mother in-law apartment - kitchen bathroom, bedroom and living room with wall to wall carpet. Fuck... I'm in the middle of this mistake right now - waiting for the insurance claim to go through and start rebuilding. I need to build the flower room back 1st because these ones will be done in veg very soon.
So DWC = Water. Water + gravity + home living area = issues waiting to happen... Just plan for the worst case scenario and it won't happen.
