Well, the baffles will actually be perforated and so shouldn't reduce the flow too much. The idea with the baffles is to spread the flow out and reduce the velocity but not slow down the flow. EDIT: Now that I think about it, reducing the velocity IS reducing the speed of the flow... that's fine as long as it still runs the 300 gph I want.

I'm looking at using a pair of MiniJet 606 pumps, 1 for each surge tank (unless I go with a closed loop, then 1 will feed the closed loop and the other will feed a single surge tank).

The whole reason for using a surge is to get flow into the tank,the trick is to do it without noise and bubbles, there is no such thing as a free lunch, you still need to power a pump to fill the surge.

I am curious as to how you settled on the one liter surge every 4 seconds.

I settled on (roughly) 1 liter every 4 seconds as a guideline for getting the flow I want in the time span I want... Here's how I figured it:

1l / 4 secs = 25l /min (around 6 gallons / min)
6 gallons x 60 mins = 360 gph or 60x turnover

EDIT: Also, I think the span between the surges have to be reasonably short, and the surge itself has to be very fast. I'm going to be playing around with 3/4" piping, I'm not sure if the flow will be fast enough... I might have to go get some 1" pipe :biggrin:

Realistically the volume will likely be less than this, more like 50x turnover because I feel that 60x might be too much? If the flow is turbulent (I'm trying to avoid this) this will be too much flow. If I decide to go with the MiniJet pumps as I mentioned before, they are rated for around 150 gph. If I bought a pair (which I would) that gives me 50x turnover during the day and 25x at night (less once you take into account head loss).

I would actually like to surge the full volume of water that will move through the display, which is why I'm planning for 2 surge tanks (one timed different and with a different volume). Still working the kinks out, I'll know more this week some time. I have to get a pail and some silicone to build a prototype of my surge siphon :lol:

3/4" or 1" for the discharge line or the fill line? Can we get that kind of release rate using 3/4", maybe even 1" if we're just using gravity and don't have a lot of head-pressure/height to push the water down into the pipe when releasing? I was just thinking about this, it would be neat if you could do a sealed container that you could pressure up with an air pump, but I suppose that wouldn't work with a Carlson surge.

Are you thinking about going with a larger diameter pipe if it doesn't work?

3/4" for the discharge... I suspect that you're right, I don't think I can move 1l of water through a 3/4" line in 2 seconds. Definitely going to larger pipe for the outputs if I need to.

The air pump idea reminds me of something called a Reverse CSD, which uses air pressure to push water out of a chamber, when a certain pipe gets exposed by the falling water level the air pressure equalizes and water rushes back into the chamber, producing the surge. I can't find the page where this device was discussed though, so I don't know how to build one :redface: I wish I had bookmarked that page.

Yeah, I've heard of those. I think if you just google "Reverse Carlson" you ought to find something. They are a neat idea but I think drawback is that, at least as I understand it, you have to have this chamber inside your tank which to me means it's likely not suitable for a small tank. Even for a regular size tank you'd want this thing hidden off to the side or the back in some unviewable area kind of thing..

You could do a RCSD by installing a couple of bulkheads on either side of the tank, low down to be the most effective, you will still hear air rushing out as you release them.

However this will cause the surge to rush OUT of the tank, not as much blast for the buck.

Hmm good point. I'm unsure of how it would look having the water level drop in the display... that said, combining a CSD and RCSD could produce some really cool effects I bet. I don't think I'll explore it though, because I don't want to buy a high flow air pump.

I'm leaning more and more heavily to using solenoids. I think that I could avoid potential problems with them if I just recognise that they have a limited life and replace them every so many thousand cycles. Part of the reason for this is that I am really considering building a controller using an Arduino. Mostly for my LED lights (got some heatsinks and fans yesterday!) but it has so much potential... temperature control, timing solenoids, etc. http://www.arduino.cc/ if anyone is interested... it will take some time but from what I've been reading it's actually pretty easy to program these things, and using one of these is right up the alley of someone who's into DIY stuff and is a little handy with a soldering iron.

It's CSD or solenoid... I'll be happier with the solenoid in the long run but the CSD will be cheaper. And won't require me to learn a programming language (which I'll likely be doing anyhow, so this point is really moot). IF I can find an online source for reef safe solenoids I'll experiment with them at least, anyone know of a source for something suitable? A 1" one would be great but I doubt if solenoids come in a size this big. I can use more than one :lol: