Started leak testing tanks - 4 hours

Now that the fuel tanks have had a good while for the last bit of proseal to set, I am ready to leak test. I was sure to buy two leak test kits. After much research on leak testing, I’ve come to the decision that the best scenario (in my opinion) it to test both tanks at the same time. This removes the every changing barometric pressure from the equation. First step was to rig up the lines that attach the clear tubing to the manometer that I am going to make. Using some short pieces of left over soft tubing, I flared the ends so I can attach them to the vent line connection.

Using a 2x8 piece of lumber I drew out a scale and used NMD90 (loomex) wire stables to secure the clear plastic tubing to the board. The marks were made at 1” gradients. I know have a large manometer. 
 
Next I took everything to my basement storage room where everything could sit and be left untouched. I then connected the fuel tanks to the ends of the manometer using two tubing clamps each (want to make sure all connections are tight). I then used some green food coloring to dye water and poured that into the manometer. I was sure that both tubes (left and right) where at equal levels. Then taking a small hand held bicycle pump I began to pump up the tanks to pressure. There is a limit to how many inches you can pump to, I’ve decided to keep things just under the recommended limit and stuck to 23”. Now since i’ve constructed my manometer so the tubing route goes down to the floor and then up.....every inch that is shown on the scale, actually represents 2” since the pressure makes the water move 1” down on the side and 1” up on the center. 
 
 
Straight away I could see that the levels where not staying put. I suspected that my Schrader valves at the fuel drain port where leaking. I used soapy water solution to check that area and sure enough they were leaking. After doing some reading, I removed the valves and applied some tite-seal sealing compound that I have (I was going to use this stuff to close the fuel access hatches on the tanks but decided to proseal last minute, glad that I was able to use the tite-seal after all) I re-installed the valves and pumped up the tanks. I double checked with soapy water....yup no leaks. Time to leave it over night and see where things sit.