Variable Speed Pumps (ability to ramp up / down)

[BetterMetalReef]

Hello all. I was curious if there were any powerheads or external pumps out there that had the ability to ramp up or down the flow rate (without the use of a valve on the output to restrict flow). I know that the Vortechs can do this, however they wouldn't really work for my application (I'd like to use closed loops preferably).

I'm thinking of setting up a vortex gyre style flow in a hex or circular tank, and I would like the ability to ramp up and down the flow rates (to coincide with the tides). The easiest way to do this would be to have an external pump that could ramp up the flow rate linearly over a given period of time, and then ramp it down. However, per my limited amount of research, I can't really find anything that can do this. Anyone know of an external pump, or a powerhead (like a maxijet analogue) that has this ability?

Many thanks for your input / .02. :D

[murfman]

Something like this?

http://www.youtube.com/watch?v=Ifd6P8mqEmI

[der_wille_zur_macht]

Zachtos's system uses a 3-phase AC pump and a VFD (variable frequency drive.) This is basically a hobbyist version of how industrial pumps are controlled, and would be an awesome way to implement your plan. If you get the right VFD, it could be totally programmable to ramp up and down, change patterns at night, etc - like his does.

However, it's a bit of an expensive proposition. First of all, you need a pump with a 3-phase motor on it. There are no hobbyist pumps built that way for marine tanks, so you're pretty much stuck - either you have to find an industrial pump that'll work (not likely), or buy a marine aquarium pump and swap the motor out for a 3-phase motor. I know several people in the DIY forum have gone that route, using the wet end from a large Reeflo pump, and the smallest 3-phase motor they could find (probably in the 1/4 - 1/2 hp range.) Figure $200 for the pump wet end, and maybe $150 for the motor. Then, you need the VFD. Cheap ones are probably $100 - $200. Then, you need all the plumbing. I'm willing to bet you'd be in $600 - $800 by the time you had the system running. Unfortunately, because of the 3-phase requirement for the VFD, you really can't scale this down to a smaller scale - there just aren't any appropriate motors or pumps smaller than the ones I'm describing.

You mention the vortech, which could be an option, and much cheaper. Another option would be Tunze controllable powerheads, which are also cheaper, and more flexible than the vortech in terms of "aiming" them to get the gyre pattern you're looking for.

Yet another option would be to find a small, external DC pump and build your own speed controller for it. DC pumps are extremely easy to control vs. AC pumps, but I don't know of any small, marine-capable DC pumps that will run externally. I also can't name anyone off the top of my head that's gone this route, while all of the above methods are somewhat well proven.

[BetterMetalReef]

Thanks for the input. Although pretty expensive for a pump, the 3-phase motor DIY looks like it might be the only way to go for what I'm looking for. The high flow rate is fine as I'd like to have a lot of flow, and by being able to ramp it down if it was too high it wouldn't be a problem.

Considering how important flow (both type and rate) is to keeping our reefs, I'm surprised the companies haven't made something more like what I'm looking for. I suppose the only ones out there to even try it are Vortech and Tunze. Still, you'd think a maker of an external running pump would throw something like this on the market.

[der_wille_zur_macht]

I agree, however I think it's easy to see that the demand (high-end reefers willing to spend money) isn't there considering the complexity. 3-phase VFD controlled pumps are bigger, scarier, more expensive, draw more power, and require lots of plumbing, compared to a controllable, submersible DC powerhead.

If you're interested, do some searching in the DIY forum, there are at least two or three threads in there where people have detailed their setups. liveforphysics was a big pioneer in this area, but I don't know if he's very active.

Basically, you want to get the wet end of a pump that'll take an appropriate motor and produce the right amount of flow. The reeflo pumps are probably the best choices. IIRC, they take a 56J motor, and you can get 1/3hp or 1/2hp 3-phase 56J motors from industrial suppliers for $150 or so. Depending on which pump and motor combo you do, you should be looking at a few thousand GPH. If you pick a wet end that's pressure biased, you can put eductors on the closed loop outputs to get a huge bump in performance.

Then, you have to pick a VFD that has the controls you want. If you just want to be able to scale it manually to X% and leave it there, you can probably find a unit for $100. If you want to be able to program it to ramp up and down, you need a unit with a frequency input, or controls onboard. Probably more like $200.

Keep the forum up to date if you put one of these systems together!

[Mike31154]

Don't you also need a 3 phase electrical supply to run a 3 phase AC motor? To the best of my knowledge the average household power is only capable of providing 2 phases.

[Whys]

3 smaller pumps in parallel, each with their own digital timer? You could use check-valves to prevent backflow to the other pumps.

[der_wille_zur_macht]

Mike, many of the smaller VFDs are designed to work on regular 120VAC houshold wiring - they bascially convert to 3-phase power internally. Of course, when shopping, you need to look for that feature unless you want to run three-phase power to your tank.

Whys, the problem with that is finding a decent-sized pump that can handle the constant on/off. Plus, check valves that won't fail!

[Whys]

Just how on/off would it need to be? I thought the OP was going for a daily sine-wave of flow velocity. That wouldn't be more than 2 to 4 on/offs a day, depending on the setup. Is that bad for most pumps?

As for pump size, how many gallons are we looking at?

I don't think a check-valve failure would be a real concern in this scenario. Wouldn't it just reduce the flow until fixed? I'm thinking of back pressure from the other pumps, not backflow from the display.

http://www.4everb.com/tripump.gif

[BetterMetalReef]

You're correct about the flow style. I'd like a sinusoidal wave with respect to flow speed (going up and down) that would have 4 maxima per 24 hours. This would roughly equate to the flow experienced out near a coast in a deep setting. Think of the fore reef. That's the habitat I'm trying to somewhat reproduce, a deep reef setting with laminar style of flow that has variable flow rates, however the rate can be quite high at times (as the tides come and go). Thus, I figured a circular (or hex/octagonal tank) would work well as it could create a vortex gyre that could have quite high flow rates, but depending on what radial position you're at you could also select different flow rates (as the water near the glass will move faster than near the surface). The direction of flow could also easily be changed as the direction of the vortex could be merely switched.

In order to do this effectively I figured using closed loops, with external pumps to draw water from the overflow, and pump it out near the bottom of the tank, thus providing not only a vortex gyre style of flow, but having a subdued flow from bottom to top #to help keep crude in suspension as this would be a bare bottom tank#.

Using multiple smaller pumps, and turning them on in succession, is something I had thought about. However, I hadn't thought about putting them in series, which is a good idea. The way I thought of possibly having it was each pump having it's own tubing, and you can imagine the # of holes that would quickly develop in the tank. I am a bit worried about having the switching put damage onto the pumps, as they would be going on/off four times a day. Check valves could be a problem as well #something that wouldn't really be needed if the individual pumps were plumbed separately, since it's a closed loop.) However, it is definitely something to consider as an alternative to creating my own pump for a grand. :)

Any other ideas? :D

[Whys]

Careful....

If you pump the water in at sand level, then more than likely, you'll be relying entirely on a check-valve to prevent your tank from draining to sand level when the pumps are off. Check-valves are well known for failure.

An alternative is to raise the return line above the DT water line and place a small hole in the line before taking it back under water. You can place a small vinyl tube in the hole and direct the stream where ever you like when the pumps are on. This way, when the pumps are off, the siphon breaks and your tank won't drain. The down side is increased head pressure due to first pushing the water higher then doing a full 180. Pumping water in under water already creates significant head pressure.

Here's a good article for helping calculate head pressure when pumping water in under water.

http://www.aquariumpros.com/articles/headpress.shtml

[Whys]

As a side note, and not a suggestion, I actually do exactly what I just warned against. I pump my water in at sand level and rely on a check-valve. I do this for a couple of reasons. One, the turbulence created by pumping water in at sand level is amazing, even at only 12x gph, and thus I have no powerheads in my DT. Two, I am mentally impaired and prepared for failure. :D

If I were to start again, I might do things differently. But doing things differently is what got me here in the first place. So that may or may not be a good thing. :lol:

JM.02

[der_wille_zur_macht]

<a href=showthread.php?s=&postid=15293068#post15293068 target=_blank>Originally posted</a> by Whys
Careful....

If you pump the water in at sand level, then more than likely, you'll be relying entirely on a check-valve to prevent your tank from draining to sand level when the pumps are off. Check-valves are well known for failure.

An alternative is to raise the return line above the DT water line and place a small hole in the line before taking it back under water. You can place a small vinyl tube in the hole and direct the stream where ever you like when the pumps are on. This way, when the pumps are off, the siphon breaks and your tank won't drain. The down side is increased head pressure due to first pushing the water higher then doing a full 180. Pumping water in under water already creates significant head pressure.

Here's a good article for helping calculate head pressure when pumping water in under water.

http://www.aquariumpros.com/articles/headpress.shtml

Whys, I would assume the OP is talking about a closed loop, which has none of these concerns.

[Whys]

Oh, well that's different. :)

Der_wille: 1
Whys: 0.5

:lol:

[der_wille_zur_macht]

;)

On another note, assuming you would be OK with something inside the tank, the Rio Polario sort of does what you're looking for, but I would question reliability - plus, with the off-the-shelf controller, the longest switch time is like 30 minutes. I bet it would be super easy to mod the controller (swapping out a resistor or something) to get your desired frequency, but now you're DIY'ing on a cheapo product and might as well spend a bit more for Tunzes.

[BetterMetalReef]

Yeah, the pumps for creating the vortex gyre flow would all be closed loops, so no worries about a back siphon draining my tank. The sump returns will be placed in other areas of the tank with appropriate siphon breaks to avoid this issue.

One pro I forgot to mention about an external pump is the maintenance issue. With an external pump it's a breeze, as I just remove the pump from the line with valves and wash it in a sink. However, if I use powerheads I have to pull them out of the tank for cleaning, which won't be that easy. For what I'm thinking about, I'm going for a deep tank with rock around a central overflow in the center. This rock would be suspended off the bottom with eggcrate, and underneath this eggcrate is where I'd like to have a decent number of my outputs (or powerheads) located. You can imagine the pain it would be to pull out powerheads from this location, and if it ain't easy maintenance typically doesn't get done. :)

As for a Rio, I'm in aggreement with zur macht and I'd just go higher quality with a tunze.

[Whys]

Hey I think I got it. 2 closed loops. P1 (small external) and P2 (large external). Sequence: P1, P2, P2+P1, P2, P1, repeat as desired. :)

[KarlBob]

Hydor recently debuted a line of controllable DC powerheads called Koralia 12V. They come in the same sizes (Nano, 1-4, and Magnum 5-8) as the original (AC) Koralias. They also sell controllers for 2 or 4 powerheads.

[Mike31154]

<a href=showthread.php?s=&postid=15292162#post15292162 target=_blank>Originally posted</a> by der_wille_zur_macht
Mike, many of the smaller VFDs are designed to work on regular 120VAC houshold wiring - they bascially convert to 3-phase power internally. Of course, when shopping, you need to look for that feature unless you want to run three-phase power to your tank.

Whys, the problem with that is finding a decent-sized pump that can handle the constant on/off. Plus, check valves that won't fail!

Thanks for the info on the VFDs. Going to have to read up on those.

[der_wille_zur_macht]

<a href=showthread.php?s=&postid=15294615#post15294615 target=_blank>Originally posted</a> by KarlBob
Hydor recently debuted a line of controllable DC powerheads called Koralia 12V. They come in the same sizes (Nano, 1-4, and Magnum 5-8) as the original (AC) Koralias. They also sell controllers for 2 or 4 powerheads.

Unfortunately, while they kept the pump prices reasonable, the controllers are extremely expensive - it pretty much puts you in Tunze territory, and Tunze has a longer/better reputation of stellar performance, longevity, and customer service IMHO.

Also, FWIW, some reports are claiming that the Koralias are really 12VAC, and hence it's not easy to DIY your own controller. See this thread for reference, where some folks tried to run them off 12VDC with no luck, but got them running on 12VAC:

http://reefcentral.com/forums/showthread.php?s=&threadid=1361588&perpage=25&pagenumber=2