google "uniseal" if you are looking for a way to drill the bottom of your buckets, hook up a pvc drain line and valve of some sorts.

if you wanted something more durable, you could opt for a bulkhead fitting, which can be found at your local hardware store.

regarding system design, im partial to having a single reservoir i can i can use to add nutrients, check ph and circulate nutrients from there. im super lazy. i have my reservoir hooked up direct to my RO water maker, with a float valve.

i usually dont leave the RO unit on rather flip a valve to the open position if the water gets low and fill for changeout.

i also have a dump valve on the bottom, to drain it.

there's all kinds of little mods you can do to be "lazy", or as i prefer to look at it, efficient.

good luck with your setup, looks like you have a good start.

Chuck

regarding the height of your plant, when I've had this problem I addressed it one of two ways:
I used metal conduit and hammered it into the ground (three of them) then ran wire around to create a very tall cage. If you got that route, be sure your plants are against a deck or something so you can reach them.
No.2 cut off all leave below the lowest set fruit and coil the stem at the base. it will keep your plants much shorter BUT it will make opening your buckets even more precarious.
As for nutrient upkeep. I always install a drain at the bottom. Get an external inline pump (not submersible) and you can pump the majority of your spent nutrient into a suitable container for redistribution. Next year simply remember to elevate the bottom of the plants. Also, changing nutrients every week is excessive. Full size plants should be consuming the majority of your nutrients and you should more or less be adding either straight water or nutrient.
I never clean my containers except between crops.

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I got tired of changing DWC bucket every week also. Now I use the same Buckets with a Dutch Bucket drip system with 1/10 the work. Once a week I drain my Reservoir completely even running fresh water and draining it. I might even add H2O2 as a cleaning agent. Then I start over again with Fresh chemicals. I put good drains in my system just to make it super easy to change water and clean the system.

I am getting ready to switching my system from my front side yard to my back yard. I plan on changing a few minor design flaws. One of changes is to get out of Florida's southern exposure and 14 hours of sun. The heat has really torn up my tomatoes.

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I'm running a system similar to yours and may be able to suggest a few things. As shown, each plant is in its own bucket with a bulkhead drain and Tygon tubing attached. Each, of course, has its own bubbler. The tubing, being transparent, gives me a visual level check. To check EC I lower the tube enough to get a sample. ( a couple of cups passed out and returned to the bucket makes the sample representative of the whole volume. ) Changing nutrients is done the same way except that I drain into a watering can so the run off can be used elsewhere. Flushing is done similarly and is sufficient, I feel.
The pots sit off the ground in a wooden rack that has a trellis six feet above from which plant support lines can be hung. Guy wires from the trellis top hold the whole thing upright in the wind. ( I learned that the hard way :) ) The only problem I've faced so far is underestimating the weight the trellis would have to hold, which is why an extra prop gas been added.

Thanks everyone. Broke down this weekend and converted the system to recirculating dwc. I think we went overboard with the reservoir bucket, 27 gallon container found at the home despot for $9. We made our own "bulkhead" connectors using pvc and garden gaskets, and attached dripsystem hoses. With the pond pump and parts, it was about $100 total. Drain from each bucket by gravity. Easy to reach equilibrium. We put all six bubblers into the reservoir instead of individual buckets, not sure why... probably should've left them in the buckets.

Reservoir is not ideal plastic and likely full of bad contaminants, but this is all just a test anyway. We harvested soil-grown tomatoes already which were started a couple weeks AFTER we started the hydro grown ones, these are just going soooo slow, very anxious and frustrated, better be good :)

Biggest mistake was putting the reservoir on the ground with no drain *face palm*. I will likely install a y-valve at the pump so we can easily pump out "most" of the water.

We tried to setup the trellis on the table, however, it kept falling over, so for now, the trellis remains as is and we'll have to deal with arching tomato plants.

I think we put the gravity drains starting at the plant buckets too high - at the base of the netpot. The plants are suddenly drinking way more water than before, and it doesn't take much to upset the balance in the recirculation, so it basically gets too low too quickly and stops draining.

If they were lower, the balance would remain just a bit longer. Drat. Won't be hard to move, and be fine with the roots as large as they are, but it is irritating.

I guess I don't understand how your system works. what is a gravity drain? any possibility you could post some kind of sketch of how it works?

Grizzman: the big water reservoir is on the ground, and has a pump which pushes water into the buckets, which are up higher on a table.

Each bucket now has a single 1/2" hole just at the base of the net pot. When water level reaches this hole, water will go into it. The hole is big enough so water level will never go above that hole. There's a hose then that routes the water back to the reservoir - and because the buckets are higher than the reservoir, gravity does the work on the water to pull it back. Easy? :)

If the hole were lower in the bucket, less water would be needed in the bucket to drain, so the recirculation occurs faster, and will last a bit longer.

Turns out my issue was actually a clogged filter - I put old socks over the pump to keep it clean, but gunk accumulated on the sock and water was barely getting pushed through into the buckets.

On a different note, I am questioning the use of vinegar to lower pH now -- pH was about 7 when I visited today, so I added vinegar into the reservoir and it foamed and bubbled up like crazy.

This is turning out to be a real pain. The pH starts to rise, causing sedimentation of nutrient, which clogs the pump, which causes the pH to rocket up over 8. Ugh. I'm ready to move the plants to soil and throw this system in the trash.

I thought the larger amount of water helps stabilize this?

What nutes are you using? I'm using GH flora duo in a dutch bucket system with 8 full grown pepper plants and I don't have any issues like you are describing with the pH or nutrient sediment.

Also, you are probably better off using pH Down to lower pH. It is stronger than vinegar so you use less.

Gen Hydo flora micro, grow, and bloom. I was in contact with their support, and they believe our water is too hard (pH of 7.4 out of the faucet, with TDS of about 350 ppm), so are suggesting we start with their micro for hardwater as the base.

I was thinking of using citric acid now instead as I have a bunch of that around the house from another project and it is very cheap (aka sour salt). pH down product seems to be nothing more than phosphoric acid.

I believe you can add ammonium nitrate to bring the pH down. It is less available to the plants so keeps does a better job of stabilizing the pH level.
BTW, if your water is pH7.4 from the tap, it seems odd it would rise as high as 8 over time. It just seems the natural pH of the water would act as a buffer and limit it from going higher.
Another option is discussed in this thread. It's a little pricey up front (you have to buy more than you need) but may prove economical in the long run.

Another follow up: we flushed as much water out as we could (in retrospect, the build could've been setup easier to empty everything, but didn't really consider that, oops), refilled, and added gen hydro micro for hardwater, their bloom and gro product. After letting that sit and circulate for a few hours, pH was well over 7, so added a diluted sulfuric acid dilution, which ultimately brought pH to 5.8. It's been stable over the last couple weeks, and we have ppm of about 850 now, down from two weeks ago of 950. With each addition of water, we've added a little Bloom product as well.

The plants are looking healthier, and new blooms have begun to develop. Yay! I'm not so keen on flushing this system now, it's quite finicky in getting it balanced like this. How exactly do I know how much and which nutrients to add, if I'm not flushing the system?