4" PVC Spools W/ Slits

[michelle_stephens]

I'm looking to add slits to our 4" PVC (Schedule 40) spools so they can be pulled off long lines after outplanting (rather than untying the long line from the anchor line).  

Has anyone experimented with or are currently using 4" PVC w/ slits to make spools spools?

I have some concerns:

1.  I've noticed when removing a large slit from the spool the gap closes, decreasing the diameter of the spool thus hold less seed string. 
2.  When cutting a small slit it makes it difficult to open the slit enough to pull 1/2" long line through.
3. I've tried thinner walled sewage pipe, but it's too malleable and causes the spool to collapse on itself. 

Anyone have any guidance? The photo below was a trial we did with 2" spools. 

[kendall_barbery]

@michelle_stephens - Have you played around with adding a removable spacer/cap to either end of the slit? Something that could hold the spool open enough to maintain the desired diameter (and therefore line length); stay in place during tank growout, and then pop off of the spool while outplanting--so that it doesn't impact the goal of just popping the PVC off of the longline after transferring the seedstring?