Vortech MP20 on a shallow tank

[AlanM]

I'm putting together a shallow 5x2, water depth will be about 12" from sand to surface, so proportions are a little unusual.

I was thinking about putting an MP20 on the end furthest from the back corner 10"x12" weir but I'm a little concerned about the shallow nature of the tank. The wet side will be at most 4.5" from the sand or surface if placed exactly in the middle, so will this result in the sand bed being sucked up or a vortex from the surface introducing a huge amount of air bubbles into the water?

The tank is going to hold about 70 US Gallons, so it's on the high end of the MP20's ratings, but I fear an MP40 will just turn it into a sand and air whirlpool.

Thoughts please.

[AlanM]

Any thoughts would help, can I dial an MP40W down far enough? I doubt if an MP10 will be enough so that's why I was looking bigger, but does bigger mean deeper?

help please

[porter_painter]

Hi Alan,

I run my mp20 about 3 inches below the service on ¾ tilt and have not problem with sucking in the air from the surface, although I have seen an mp40 doing exactly that.

If you can wait until the weekend when I have some time, I can do a little experiment for you and put the mp20 about 4 inches from the bottom for you and run it on full power.

My initial thoughts would be that you may have more of a problem with the powerhead blowing the sand away rather than sucking it up – but this could depend on the size of the substrate.

Cheers
Andy

[just-reefin]

Hi Alan,

I have a MP20 in my RedSeaMax 130ltr in addition to the supplied stock pumps . I have this set at about 75% power, 4" below surface, 12" above substrate, & never have a problem with sand being blown about. Even on 100% full power with this unit no sand is shifted tho my substate is only 1 -1.5" deep.

I know every tank is different (ie: amount of live rock & positioning, Other pumps, tank shape & size), but I reckon you could get away with an MP20 even tho your tank is gonna be 5' long. The surge from this pump is strong yet very broad, unlike a stream effect from lets say a powerjet!

Playing around with the power % & pulse setting I'm sure that you will create enough of a wave effect within your set up. IMO a MP40 would be too powerful (tho you can turn the speed right down) & more expensive to buy & run.

Hope this helps a bit,

Keith

[AlanM]

Thanks guys, it does look like an MP20 will be a good thing for my tank. Bit of an ouch on price, especially when coupled with a batter backup, but its a valuable bit of kit.

[Dami]

I ran one of my MP40 new gen in 10inches of water with no problem.... (4 x 3 x 1")
Only issue was the fish struggled to swim it..... :laugh:
you'll only need one in there thats for sure... :laugh:
found mine moved everything around (in a good way), not the substrate, just moved the entire tank volume... sucked out any detrius and swept it away better than deep tanks.
ran the MP40w at 3/2's volume on pulse long pause (hardest).

Vortechs have a blank (solid) section on the wet side that you put on top... this stops the air being drawn from the surface. and the undertow will move things a little, but once settled it'll be no problem.

:wave:

[AlanM]

Thanks Damiano, this tank is a 15" high 5'x2', with 33cm water depth (from base to surface), puts it at just about 70G so on the edge between the "official ratings" of the MP20 and MP40.

The fish can take their chances - they may have grown lazy in the low turnover nano, it'll do them good to get some exercise.

[Roshan]

Alan - I run a 4x2x16" shallow sps tank. I have one mp40w and it sits at one far end about 4" below the surface. I run mine on reefcrest as its an sps tank. Does the job pretty well. Mine is on 3/4 power. I would suggest you go for a MP40w rather than MP20. You may find that the MP20 wont be powerful enough over time as you system grows.

My tank is rimless and the only thing I found was that placing the MP40w two high caused some water spillage over the top - not a problem lower down for me as I run my system barebottom.

Vortechs are good bits of kit but if I am honest then I have to say they could be better as I've two faults on the wetside in less than a years ownership. Credit to Jez and ITC as they've resolved the issue asap. Overall they are still the best out there at the moment for overall looks and functionality.

Hope this helps.

Roshan:)

[wayne in norway]

I think you'd be ok with an mp40 in one reefcrest mode. Mine is only 6 inches below the surface and has never even looked like getting bubbles down that far. Fine sand will be tricky tho'

[AlanM]

The sand issue isn't really an issue - the tank is bare at the moment other than some koi filter grid and it may stay that way for a while. Courser grains rather than fine sand would be the only thing going in, I'm not planning on having any sifters in there, but if I do then I'll put in a sand zone away from the drag of the Vortech.