Ok, here's what I have for my DIY "python".
1)Faucet to garden hose thread adaptor (Lee's makes both a plastic and metal one... spend the extra buck or two for the metal one, well worth it)
2) Water Bed Pump from Walmart. This may be the "blue thing" you're refering to. On one end there is a female garden hose thread then 90 degrees to that is a male garden hose thread. On the bottom is a "valve".
3) Female garden hose thread x quick adaptor put on the male thread of the WBP.
4) Garden hose of what ever length you need. If it's too long... cut it. The less hose there is there, the better it will operate. Also, ideally go with a 5/8 or 3/4 ID hose. 1/2 ID just restricts the flow (and yes, yes I know python uses 1/2)
5) Quick connects for the garden hose.
6) Quick connect x male thread adaptor
7) Female Garden hose thread x hose barb adaptor that gets #6 threaded into it. The hose barb should be what ever size hose your gravel vac has.
8) Gravel Vac with short cut hose (like only 3 inches at most).
So that will get you the basic python system. I do water LARGE water changes OFTEN so I use a slightly different system so the water isn't wasted during draining. What's below replaces #'s 6, 7 and 8 on mine 99% of the time.
9) Mag 12 pump
10) Female 3/4" NPT x garden hose thread adaptor. This goes on the outlet of #9.
11) Female garden hose thread x quick connect this goes on the #10.
So all I do is drop the pump in the tank, connect everything on up the line to the sink (making sure the WBP bottom valve is open) and plug in the pump. When it's drained, I unplug the pump, close the bottom WBP valve, turn on the tap and dose the tank with prime. Then when the tank is full I open the bottom valve, lift the pump out, disconnect the hose from the pump and coil the hose draining it in the process with help from the WBP.
LOL, it sounds a lot more complicated than it is
. All in all a +80% W/C in my 90 takes less than 45 min to complete and I never have to lift anything heavier than the Mag 12.
Chris