PVC Overflow FAIL

Today I did a partial water change on the turtle tank. I was getting sick of seeing the cloudy water and the water was also starting to tan from the wood that is inside the tank. I siphoned out half the water and put in brand new water that was dechlorinated and treated. The tank was at about 80degrees before I changed the water and dropped down significantly. So tonight I turned off all the lamps but kept a heat lamp on. Hopefully by tomorrow the water will warm up so the turtles dont get too cold.
I tried to finish my PVC Overflow today. Of course I wanted to make sure it worked and ran properly before doing a DIY post on it. I bought 1/2 inch PVC, PVC connectors, One way valve, and tubing. These are the materials needed to make this overflow. I've made a PVC overflow before so I already had a PVC cutter but I couldn't find my PVC cement. I then thought "maybe I can seal everything with a hot glue gun." Boy was I wrong. Water didn't leak but air was getting inside the overflow, making the overflow a complete fail. Water was rising in the tank, decreasing in the sump, and water was not going down the overflow. If I did not catch onto this sooner, the tank would have flooded and my room would have been a mess.
I did start building my sump today though. I got a pack of 5 shoe box containers from target and cut off the bottom of each box. Then I drilled holes on the lid (for trickling). In all, I stacked four out of the five shoe boxes. This isnt the sturdiest trickle filter but I plan on using silicon to keep them all together. I like this idea because when I need to change the filter medium, I can just unlatch the layer and clean. Then put the lid right back on. It is pretty convenient. Using a plastic drawer would be even more convenient but the cheapest plastic drawer was $15 where as the shoe boxes were $5. Also, the plastic drawer would not fit into my 20gallon tank and I'de probably have to buy a larger tub which is more money to be spent and more space taken up. The Trickle filter I made is sitting in my 20gallon long tank that I had. (I will post better pictures of the anatomy of the filter once I get all the filter mediums) I ordered a pump on ebay for $20. It is a 370GPH submersible pump. (link at the end of post)
I now realize that my 1/2 inch PVC overflow will not be able to handle the 370GPH out take. So tomorrow I will be heading back to home depot and remaking my overflow with a 3/4 inch PVC instead. I wont forget to buy the PVC cement this time. haha. Hopefully I get the pump this week so I can finish my filter system. I cant wait for it to be up and running. Then I can take better pictures of my turtles.

OH! I forgot to mention. I haven't thought of any names for the turtles yet. I have to think of something unique. Hahha. Right now, they are nicknamed Koopa and Troopa. haha

Link for 370GPH pump on Ebay:
http://www.ebay.com/itm/261032997754?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649