Need some help with Ebb-n-Flow setup

Hi just trying to setup the ebb-n-flow system but running into some problems I had setup temporary to time the fill and how many gallons I would need, I have the tray on some saw horses with 1x3 under the tray.


I then started to run pump and stopwatch but noticed the tray bowing in the center and no water reaching the net pot I had put to check if I needed more water once reservoir was empty, so far I had 20 gallons in and it didn’t reach the pot. So I’m here looking for help on how to brace tray and how much of an angle to slope to drain currently it one full bubble off center on a 4ft level. Help on this would be appreciated thanks in advance

I ditched the saw horses and built a frame out of 1 inch pvc

Ok decided to build a 2x4 frame with bottom braces to fix the buckling problem hopefully I can get this going in the next week, also my plants were in 1inch rockwool starter cubes but the got to tall so put them (with rockwool cube) in a solo cup and topped with potting soil what would transplant recommendations be as I had planned to use 4in rockwool I was thinking of stacking two of them and packing loose rock wool around stem so any other surgestion???

Here is how I run my flood table and imo the best way of growing in water is ebb and flow.

Table is level, flood and drain nozzles right next to each other.
I do 15min floods every hour, and because I use such a small pump it takes almost 15mins to fully flood my table. Run a bubbler in the res.
The table is cover with panda plastic, clones come straight out of my cloner with just roots into 6in netpots then bury the roots in hydroton, I avoid rockwool, I see no point in using it.