MP40s at 20%... do you get any speed variations?

[benj2112]

I am trying to get my 2 MP40s set so I have minimal sand bare spots. I am wondering if I set them at 20% (which I believe I read was the minimum for control even if you set them lower - am I wrong on that?), do I get any speed variation with the different programs like tidal swell or reef crest?

I am currently having a heck of a time getting them set so I don't have a bare spot after 24 hours or so in front middle of my tanks (4ft 120 gallon). I have special grade Caribsea sand, which I was hoping would minimize bare spots.

Thanks for any info or tips/advice.

 

[ryeguyy84]

How low do you have them in the tank? My 40s are at 80% on my 90g

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[benj2112]

A few inches from the top waterline.

 

[ryeguyy84]

Hmm is this sand new?

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[benj2112]

Yes, it is newer sand. The tank has only been up for a few few months.