And on this day Poseidon said "Let the seas surge to and fro!" He looked upon the frothing waves and saw that it was good, very good.
Ah, surge. The reef keepers' Holy Grail. What drives us to attempt to recreate this complex process of water movement? Does the tank seem more "real¨ if the animals are swaying back and forth or do we do it because we think it's the most beneficial type of flow for them? I must admit, my reason for doing it is likely the former but I'm not above using the later as justification.
There seem to be as many ways of creating surge as there are names for them.
CSD (Carlson Surge Device)
RCSD (Reverse Carlson Surge Device)
Borneman Surge Device
Dump Buckets
Etc.
And that doesn't take into account things such as the Tunze Wavebox or Oloid devices and anything else someone can dream up to create back and forth water movement.
As always, I'm not only here to pontificate but hopefully to educate as well. Here are a few threads for reference on surge devices.
http://www.petsforum.com/personal/trevor-jones/surge_device.html
http://reefcentral.com/forums/showthread.php?s=&postid=4116486
http://www.aquatouch.com/surge_b.htm
http://web.archive.org/web/20050711221839/http://www.planet-reef.com/surge1.htm
http://www.petsforum.com/cis-fishnet/seascope/00SS1705.htm
These are just a few I had handy. A quick Google search will reveal many, many more links for your browsing pleasure.
The problems common to almost all surge devices are bubbles, noise, bubbles, salt creep, bubbles, mechanical failure, bubbles, and oh, did I mention bubbles? Many of the pictures and videos I¡¦ve seen on surge devices have had an ungodly amount of bubbles associated with them. Now, this isn't necessarily harmful to the animals in the tank (ever seen the underside of crashing waves?) but to many it's not aesthetically appealing. The eye of the beholder and all that...
Noise and bubbles were my biggest concerns as well and I did experiment with an internal CSD which is basically a bell and siphon concept but I didn't take it too far because I didn't feel I could eliminate enough bubbles that way. Instead I opted to go with the Borneman flapper design but I was still worried about how to minimize the bubbles and quite frankly the toilet flushing noise. Well, as I was browsing the plumbing aisle at my local Home Depot, I happened across this:
And what he saw was good, very good. (Queue breaking clouds, rays of sunshine, and angelic music.)
Well, maybe not the Holy Grail but I had a suspicion that this type of flush valve would be the key to minimizing bubbles and noise and I was right, but more on that later. The rest of the device is basically a vessel of your choosing (I chose plastic storage bins) and the various fittings to facilitate the transfer of water.
Next step was to figure out how to make the valve go up and down. Obviously some sort of flotation device was required and airplane seat cushions were not going to cut it. I experimented with lots of silicone and lots of ping-pong balls (yes, I said ping-pong balls) and suffice it to say, that didn’t work out very well. I ended up using (surprise!) plastic toilet tank balls. I attached them to the flush valve with plastic chain, plastic machine screws, plastic washers, and plastic wing nuts. It may not be very pretty but it’s functional. It does take two balls to overcome the suction generated between the flush valve and the rubber washer. Ok, that’s about enough snickering from you in the back. This is a serious scientific discussion not health class. I don’t care what you think this looks like.
One thing I did learn with my experiments is that is takes a good GPH flow to over come the hold of the rubber seal. Too slow and the float valve will raise off the seal just enough to allow the water to trickle through at the same flow rate it’s coming in and not release the entire surge. I don’t have an exact calculation of what the flow should be but as an example, I’m feeding my surge with a Sequence Dart run through an Ocean Motions Squirt and if I had much less flow, these devices would not operate properly. YMMV.
Finally, a 2†FPT PVC will thread directly onto this flush valve and that’s what I have running to 2†bulkheads on my tank. I do not have additional directional outputs on the bulkheads because I have found that by doing so, the bubbles are more noticeable. I have bubbles at the beginning of a surge but they quickly dissipate by running the bulkheads unobstructed. Honestly, I think the reason I have any bubbles at all is because I placed the bottom of the flush valve higher then the water level in the tank so after the surge ends, air is trapped in the plumbing. Air does not enter the outflow of the valve as the surge starts and I don’t believe its being drawn in from the overflow tube. I truly believe that if I have drilled the bulkhead holes lower in the tank so the bottom of the flush valve was under the water level, bubbles would be nearly non existent. This is the most bubbles that my surge generates as it is.
As for noise, there is a wooooooosh of water but not a flushing sound and there is a slight thud as the flush valve closes. Since my tank and surge devices are behind a wall, it’s not that distracting to me. Again, YMMV.
I do plan on replacing the container on the right in the picture as I have found that it’s not quite tall enough and the lip of the container allows splashed water to seep out causing dripping and salt creep. The container on the left does not do this.
One other thing, the bubbles from the surge do burst at the surface and cause salt creep around the tank. I keep it in check by keeping it clean and if you decide to do this, unless you have lids on your tank, it’s something you’ll have to live with.
Well, that's about it for now so if you have any questions let me know. And for pity's sake you can quit laughing at the picture of the flush valve and toliet balls. :hmm2: