Looking For Ideas On Oscillating Return Flow

Discussion in 'Resources' started by fingerwrinkles, Mar 30, 2011.

  1. I'm in the process of plumbing the new tank and came up with the bright idea that it would be interesting to have the return flow mimic the bidirectional flow that is found in certain areas such as barrier reef channels. Since the tank has two return ports (one in each corner), I thought I could oscillate the return between the two corners on 6 hour cycles (with perhaps a bit of overlap) in order to mimic tidal cycles.

    The only ways I can think of doing this is to go with a pair of actuator valves (one for each return corner) driven by a timer. Another possibility would be a single 3 way actuator valve, but this reduces the movement to one or the other and does not allow overlap. The positive to this approach though is that one side will always be open, unlike the pair of valves approach where they will be closed unless they are powered open (unless I get valves that are open in the power off position). Therefore, if the power goes out on the tank circuit while the pump in the garage may still be going, the pump won't be pushing against a closed valve (unlikely to be sure, but still a possibility with potentially messy consequences). The challenge here is that either of these options are terribly expensive (several hundreds of $$) and I'm not sure the benefit is really there).

    Further down the list are devices such as Oceans Motions, but these are on a very short cycle and are really more wavemakers than current directors.

    If anyone has doone anything like this, or has suggestions on how to do this somewhat economically through the application of equipment from other hobbies / industries, your thoughts would be most appreciated! I had looked into using valves from pool and spa type places, but unfortunately these are not made for saltwater application.

    Thanks!
     
  2. Mr. Ugly

    Mr. Ugly Past President

    How about 2 small eheims on timers? One for each return.

    But wouldn't your in tank circulation contribute more to water movement than your return flow?
     
  3. GDawson

    GDawson Guest

    There are saltwater pools at health spas/retreats. I don't know pricing but the equipment does exist.

    -Gregory
     
  4. sfsuphysics

    sfsuphysics Supporting Member

    OM, is extremely short cycle (1 minute to go through all 4 directions IIRC) and to be honest I wouldn't even call it a wavemaker.

    For long period, can't really think of anything except what you already did, I recall looking for PVC valves and they're expensive... however I also saw those pool ones, not sure if this is the same brand as you looked at, but it's worth a shot. I'm guessing though at these prices there's some hunk of metal somewhere in there that contacts water
    http://www.swimmingpoolsetc.com/intermatic-valves.htm

    IMO your best bet is by using pumps in the tank. Something like Tunze pumps on an aquacontroller, to allow you to get LONG duration flows... you could probably do the same thing with Vortech pumps too, but you'd have to put them on an on/off timer not sure how they interface with any controllers on the market today.
     
  5. Mr. Ugly

    Mr. Ugly Past President

    Valves and actuators. More stuff to buy, more stuff to maintain, more stuff to break.
     
  6. sfsuphysics

    sfsuphysics Supporting Member

    Could always use an off the shelf PVC valve (something like a gate valve that moves smoothly) and use an electric motor to rotate it... however I can see all sorts of issues with going that route.. but if you're feeling like MacGyvering something together could be fun
     
  7. rygh

    rygh Supporting Member

    I pondered similar ideas. Basically, a good saltwater valve is simply too expensive. In fact, an extra pump is possibly cheaper.
    Sprinkler valves might work, but not particularly reliable, and have brass parts. So not a good idea.
    Thought about multiple pumps, but there are two downsides:
    1) A lot of return pumps are not built to start/stop that often.
    2) You have to align the start/stop times, such that both are not on at the same time, or both are not off.

    In the end, I decided on the more basic approach, mentioned above:
    Bunch of powerheads on a controller.
    Far more power efficient way of moving water as well.
     
  8. Thanks for all the good suggestions. I did check into the pool type valves since I was thinking the same think about saltwater pools and spas. However, one manufacturer advised that the valves have exposed stainless screws inside the pipe, and the rating is good only to 5000 ppm NaCl. Since seawater is supposedly 35,000 ppm (give or take!), I decided that was not something to fool around with.

    Norm, you did hit on the head one of my worries, not to mention more stuff = more joints = more possibility for leaks. Since I've got a zero tolerance policy there, simpler is better which complicates the challenge.

    I will have a set of Tunzes in the tank, so this is just for the return. Since the sump is about 50' away in the garage I can't do a pump for each return, but that also would be a good idea if the distance was closer and the lines weren't already run.

    Seems like I'll be scratching the head for a bit trying to see if this is possible, and all ideas welcome!
     
  9. Mr. Ugly

    Mr. Ugly Past President

    Solenoid operated PVC diaphragm valves at your outlets. But those start at several hundred dollars each.

    Or you could connect your return outlets to your piping with tygon. Then DIY a couple solenoids(or linear actuators) onto the tygon sections to make them work like pinch valves. Not a big deal if they don't close off completely either.

    Your routine maintenance will require periodic replacement of the tygon. Whether or not it shows wear.
     
  10. Erick

    Erick Guest

    what about a powerhead strapped to a pipe that is strapped to an oscillating fan? It cools the tank and moves the powerhead two birds with one stone!
     
  11. sfsuphysics

    sfsuphysics Supporting Member

    I might buy one of those cheapy pool ones and just see if any of the exposed screws actually can be reached, perhaps even replaced with nylon screws.
     
  12. Actually the "cheapy" pool ones are about $160 with the actuator, so a bit much for a "try or toss" toy ... maybe the cheapest option is the put in two manual valves and then give one of the kids a couple bucks to turn them off / on a couple times a day!
     
  13. Matt_Wandell

    Matt_Wandell Honorary Member

    We have a few tanks at work that do this. Just pairs of in tank powerheads and 2 timers. 4-6 hours on each, 15-30 minute overlap. Rinse, repeat.

    I looked into doing it on a small tank and the conversation in my head went very much like this thread. I almost had a digital timer wired up by a tech-geeky friend that could turn an OM on for 30 seconds so that it would perform like an automated ball valve. Then I consider using solenoids and all kinds of gizmos. All overly complicated. 2 pumps is the simplest most foolproof way. And I would definitely not involve your return pump/s in case it decides not to turn back on when it's supposed to.

    The fancy way to do it would be with Vortechs--I believe the newest Ecosmart conrollers may even have a feature that allows for pulses of several hours duration.
     
  14. GreshamH

    GreshamH Guest

    I used to work on aquariums with various electronic ball valves. OUr Asahi America valves needed yearly maintenance and only last like two years tops (or at least in our systems). Haywards 3-way electronic ball valve was MUCH more expensive, but it's going on over 10 years with NO service needed.
     

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