Advanced Reefer
I have a 70g reef with ~500 gph total water movement. I understand that I need more for SPS, but how much more? There are 2 170 gph PH's, one on the left, one on the right. My HOT skimmer puts out maybe 160 gph. Would it be enough to add a MJ 900 (230 gph) in the middle, or do I need more than that? Keep in mind MO purchase is not an option for this, so I have to get it at the LFS...$$$$.


jimmy n

Advanced Reefer

Sounds like you're ready for that sump and seaswirl on return. A "rule of thumb" (granted I see no value in rules of thumb) is that tank turnover should be greater than 10 x/ hour.

With that being said, I turn my tank over 20 times an hour with a tunze wavemaking system. I just recently began, but I think I'm already seeing some results.



Advanced Reefer
I am to the point where I don't think you can have too much current (almost). I have 2 Iwaki 40 RXLT on my retun and 2 closed loops using a MAG 12 and a MAG 18. When both closed loops are on at the same time (about an hour a day) I am pushing a little over 5000 GPH. At the minimum I am getting 20x movement and maximum is 30+. I have a 150 with mainly SPS and LPS. I do have my LPS positioned under cliffs or overhangs so they do not get the brunt of the movement, but my SPS love it. I think I read once that mother nature (during a storm) can move water at 50-100 feet per second. Now I am not trying to duplicate a storm, but that shows how much force they can actually take.

I would shoot for a MAG 7,9, or 12 in a closed loop or add a few more PH's. HTH


Advanced Reefer
Thanks. Now I'm thinking of getting 2 or 3 more PH's instead of one (I cannot afford a sump right now).

I'll have to get them online then. It will be fun fun fun to convince my parents...

How does one MJ 1200 and one 900 sound?


Advanced Reefer
I think it's important that the movement be dispersed. I run 300gph each through 2 sea swirls with y outputs and a spray bar with 30 eighth inch holes on my 15g sps tank. It turns the tank over 60 times per hour but it's fairly evenly distributed.


Advanced Reefer
I agree that the water motion is much better if it's random and "dispersed", rather than a constant non-moving jet of water blasting away at a coral or two.


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