We spent a good week licking our wounds and now it's time to move on. One thing we knew when we took on our first grow of this size was there was going to be a learning curve, and we'd learn from hands on experience and make changes accordingly. As far as cleanroom protocols, we are now dialed in and have made changes.
Moving onto the mother/veg room, one issue that drove me nuts was how fast algae would grow in our 4'x8' flood tables. I was having to clean them out about every week, and it was a very tedious process. After the first time, the gears in my head began turning. I needed a better solution, and knew it was the lighting creating the problem by getting to the water in the flood table. I NEEDED a light proof top of sorts, so I began researching for something so obvious there had to be dozens of viable options, and in all sorts of sizes. Guess what? I must be the only person on planet earth with this issue. Oh well. So be it. I'll do all I know to do.
Build it myself.
First up was finding a material capable of spanning a 4'x8' flood table, prevent light from reaching the bottom of the flood table, be lightweight, waterproof, durable and affordable. I looked at the standard materials like Lexan, Plexiglass and others. First thing I noted was 1/4" thick material in either flavor wasn't ridged enough to span the table, and to get a piece of 1/2"? WAY too heavy.
After a few days of searching, I came up with an option and couldn't wait to get my hands on it! Phone salesman talk is cheap and I'm a hands on kinda guy so I planned a trip to put my hands on this material. Once there I determined it was available in 4'x8' sheets and was a full 1/2" thick. When I reached down to pick it up I instantly felt like Superman. No fricking way, right? Indeed. Ridged. Thick. Lightweight. Waterproof. BINGO! What I ended up with was a 4'x8' sheet of EXPANDED PVC. Yea I know, Sounds cheesy but it's EXACTLY what we need.
Now, I needed to decide what to use to hold plants and how many could I get on a 4'x8' table. I determined a 5 inch net pot would allow me to get specifically 98 plants per table. I also decided right off to build this using two 4'x4' pieces instead of a 4'x8'. I have to cut a LOT of 5' holes. 49 per end.
Also, a 5" hole saw isn't cheap. Like 60 bucks or so, however a cheap 15 dollar harbor Freight kit will work just fine here.
Yes. It took a spell to drill all these holes. The silver lining is it's a one-time affair and should allow me to get through an entire cycle without dealing with algae.
Even though this expanded PVC is pretty stiff, the edge in the middle of the table where the two pieces meet don't have any edge support and droops in the middle.
I needed to keep it as light as possible, so I opted for a piece of 3/4" aluminum angle 1/8" thick and used machine screws to attach it to the expanded PVC.
I then wrapped the three edges with 1/2"x3/4" weatherstripping. No light leaking! This also put the net baskets about 1/16" of an inch off the bottom of the flood table.
I only had one mishap. I forgot to account for the fill and drain fittings, and had already cut two five inch holes where they are located on both ends of the table. A net basket won't fit here, so a work-around is needed. Now, I do need to be able to access these fittings, and it would be nice to do it withtout having to remove the entire top, so....
A piece of leftover angle and a cheap drawer pull with a piece of insulated bubble wrap sandwiched between them. Lightproof and easy access!
Here's a view of one side completed. This gives me 48 plant sites per side.
Here's a view from the side. Note how close the net pot are from touching the bottom of the flood table...without actually touching.
One more side to go. 48 more 5 inch holes.
Boom! Done! This is going to be a real timesaver and be able to keep the flood table clean and algae free! Now, since it's now proven, I need to make one, maybe two more...
Anyone who uses a flood table should be able to really appreciate this mod. Why a simple injection molded top for these tables isn't available is beyond me.
Guess now, I don't need one anymore.