JBJ 1/4hp minimum flow?

markw78 · Apr 21, 2021

The minimum flow is like 450gph, but I've read as long as it's not too low, you can go less...

What are the chances I can run it with an old Magnum 350 that's already running through a reactor? I have no idea how much flow it is, but it's fairly low.

It sounds like if I were to try it, the things to look out for are icing on the chiller/compressor? and knocking/noises etc?

Or should I not even try it?

My other option is a Fluval FX6, which is apparently 536 GPH (feels higher but I guess not). These are the only 2 pumps I have, I would much prefer to use the Magnum and leave the Fluval loop OEM, but I also don't want to ruin this new (to me) chiller

Thanks
Mark

ca1ore · Apr 21, 2021

Not familiar with that unit .... where is the temp probe located? If it’s in the chiller chamber (as mine was), too low flow will short cycle the unit. If it’s somewhere else then icing up is the main issue. I always prefer to run my chillers at the high end of the flow range.

markw78 · Apr 22, 2021

Thanks for the feedback! I am not very familiar with the unit either, just bought it used from someone else who had bought it used... does anyone buy NEW chillers? lol... literally just got a chiller and a pair of hoses. Have been doing some reading on the topic, this is for a freshwater planted tank, so I'm not just turning it over 20x an hour like a reef lol... no one in the FW world knows a thing about chillers, this forum had the most recent questions/discussion so figured I'd join and ask!

schuby · Apr 22, 2021

I use the 1/5 hp jbj chiller and it works well for my 150 gal DT with 40 gal sump. Bought it new more than 2 years ago. I push 300 gph (known because of inline flow-meter) through it and have not had any issues. Recommended flow is 480-1320 gph. I had planned to push about 500 gph but my plumbing plus chiller creates too much head-pressure for my pump. My second return pump, running at 40% less power than other pump and sans chiller, also pushes 300 gph. I have a net 110 gals of water in DT so I'm getting about 5.5x turnover of my DT at 600 gph.

I'm pretty sure JBJ chillers have a freeze-protection circuit that will shutdown the chiller if there's not enough flow. I've never experienced it. Also, I have my Apex turn my chiller off when my return pumps are off or the flow rate is less than 200 gph.

ca1ore · Apr 22, 2021

markw78 said:
Thanks for the feedback! I am not very familiar with the unit either, just bought it used from someone else who had bought it used... does anyone buy NEW chillers? lol... literally just got a chiller and a pair of hoses. Have been doing some reading on the topic, this is for a freshwater planted tank, so I'm not just turning it over 20x an hour like a reef lol... no one in the FW world knows a thing about chillers, this forum had the most recent questions/discussion so figured I'd join and ask!

Took a quick peek .... appears that the temp probe is inside the unit. You will just have to experiment with it. You want to avoid short cycling - compressor turning on and off too frequently. Chap that makes mine told me a couple of on/off cycles per hour is a good target.

markw78 · Apr 25, 2021

schuby said:
I use the 1/5 hp jbj chiller and it works well for my 150 gal DT with 40 gal sump. Bought it new more than 2 years ago. I push 300 gph (known because of inline flow-meter) through it and have not had any issues. Recommended flow is 480-1320 gph. I had planned to push about 500 gph but my plumbing plus chiller creates too much head-pressure for my pump. My second return pump, running at 40% less power than other pump and sans chiller, also pushes 300 gph. I have a net 110 gals of water in DT so I'm getting about 5.5x turnover of my DT at 600 gph.

I'm pretty sure JBJ chillers have a freeze-protection circuit that will shutdown the chiller if there's not enough flow. I've never experienced it. Also, I have my Apex turn my chiller off when my return pumps are off or the flow rate is less than 200 gph.

Thanks!

What flow meter are you using?