not new, but, loop siphons

[Apollo]

Not sure why you need a 1 1/2" loop, I have two 300 gal GB's that will drain around 150 gals each in just over 3 minutes. My 3/4" fill pipe will then take about 8 minutes to refill the GB's.

How large is your FT? At a flow rate of 86 gals per hour the water turn over in your tank seems insufficient. With such a small pump it seems like you should be able to use a much smaller/inexpensive loops siphon.

I'm still pushing the "Pipe Siphon by Apollo" you could drain it though your side connection. Place the Pipe Siphon in the corner, bury it in the media, then plant radishes, carrots or any plant with a smaller root mass above or around it.