SQUARE it hold water better and will always suck all the way back.  Cheaper too. :0

Square!! I don't feel guilty if I chop one up! I cut 1" or so off the corners, fill them with soapy water, and I've had them last almost as long as the balls! I used to run a 47m Schwing, and the balls could be a problem when they got water fat, but trimming the squares really helped. I still trim them a little.The best way to trim them is with either a hand or a hacksaw blade.

I use the squares, but I will definitely try the two rounds tied together, seems like a gooder.

BTW did you guys see the picture on this site of the guy with the prime port/stopper? WAY COOL

Oh ya, and Raymond's sponge on a rope is great too.

and the picture was piccasso-esqe

try this setup... we used to get buildup in the deck pipes using only one square sponge, no longer an issue since switching to this setup, and priming has become much less "eventful"... It's a bigger investment up front, but theses round sponges seem to last forever... as long as you don't chop them in the hopper

I like 2 use the square sponge better seams 2 wipe the pipe better.People r always asking me "how much water it takes me to clean those pipes" and they r always shocked at how easy it it when I suck the sponge back.

Foam cylinders always worked best for me with 5 gallon bucket of water. How I learned as a kid then water washed when I started pumping. Two orange sponges just cost to much when someone else runs your pump eather chops them up for ya or dosent wash them off. You only out a few bucks for a foam cylinder.

that's why you pack them around in your lunch box LOL... it's easier for us to monitor sponge usage/abuse because we are a smaller outfit, but I can definitely see how it could be frustrating in a larger company where there is always that "one guy" ...

Yep, I learned with the foam cylinders.  They are the best but we could never find them when I changed companies.  Where do you get them?

NO SPONGES, JUST WATER WASH!!!

Look for a company that sells pigs for large plumbing. I know the company I use to pump for would get them for maybe 4 5 bucks a piece instead of 50 or 60 for a good foam ball. When I was a kid and my dad has his own little company we used large nerf balls. Put a little of oil on the ball and swell it a bit. Chase it with water when you suck back. But learn to water wash as a back up just in case you forgot to check for one when you left.

like a high rise go devil the blue ones I just grind it down And i would suck it back Idled and speed on number 1 on a schwing for a boom ,for a high rise an air compresser one go devil and a sponge a round poof ball the go devil first and the the sponge with one 5'' tip hose full of water and for trailer pumping I like to take the reducer off and clean the valve and cylinders place a peace of a sponge in the reducer varing in size depending in the hose size and pumping it out with water I have pumeped a full bran new poof sponge threw 2'' it was pretty funny looking seeing that big sponge coming out that 2'' hole