Conversion from side mount cartridge pump to sand pump adapter question

[Cervy]

I am currently planning on converting from a side mount cartridge filter pump to a sand pump. I plan to use the cartridge filter pump housing just so I don't have to close up the large inlet in the liner. My thought was to just attach the new sand pump inlet hose to the old cartridge pump outlet. Then use a B adapter to attach the sand pump filter outlet back to the pool and jet/outlet. My question is on the outlet of the cartridge filter is just a male 1.4" fitting and I need to attach the new 1.5" hose with screw fitting to it. What type of adapter do I need to do this? The 1.5" tube is too rigid for a pipe clamp.
Pool is a 18' diameter round, 54" height, chlorine.
Upgrading to intex Krystal clear 2100 gallon sand pump.
Any help is appreciated. Feel like I am missing something really easy here. Hahaha

 

[Cervy]

Found a video that used a 1.5" flexible pvc coupling with hose clamps. Looks like that would work good. So then I could go from cartridge filter to this flexible coupling to a B adapter, to inlet hose.