[DJ88]

Hey steve.. there are devices out there for doing surges.. Is that what you are looking for?

If you are trying to recreate the flow on a reef keep this in mind. You would have to have a flow of 48,000 gallons per hour in a 100 gallon tank. Something we can't attain in a tank.. You are talking about massive pumps there. We can get 2400 GPH pumps. but a problem with having that blasting out of a nozzle in your tank is that it isn't good for your corals to be hit with such force. I have had a coral's tissue recede when a maxijet fell and blasted it for too long. It took a fair amount of time for it to recover. Most won't.

Tides aren't really water movement like most people think.. It is the ocean rising and falling.. That is it.. it is the waves and currents that you feel when diving and what gives the corals the nutrients they need. To me, when you say tidal action you are talking about raising and lowering the water level in your tank to mimic the action you see on shore. If you want to have water flow you are talking about currents and wave action created by the winds(which we try to create with powerheads and pumps), semantics I know.. But those are what tides and currents are. Tidal surges you see in a harbour or on the beach are caused by the water moving up along a shoreline or a channel. When we were out at sea we never saw the tides moving and changing. We didn't have a reference point. On a reef the rising and falling of the tides isn't perceptible. But currents created by wave and wind action are.

One of the reasons for having the wave action and circulation in the tank is for aiding in the removal of wastes to the sump and then the skimmer. Without this higher flow it(wastes) will deposit itself on the rocks and break down in your tank. Which we really don't want. Too many wastes breaking down can lead to algae, cyano and can cause different problems with corals if it builds up on the corals and isn't removed. RTN is one of these, receeding of coral tissue is another. No growth at all is another possibility

The higher flow and random flow helps bring nutrients to the corals. Phyto, minerals etc. Calcium. By lowering this flow you may not replenish the needed or desired nutrients..

IMO, I find the best growth appears on corals in a tank with water flow from a sea swirl. Cycling power heads on and off is another cheaper option. Closed loops sytems area n added bonus and I am concidering it with my 120 when it is built. Those are the options I will chose to use.

If you can stand the noise and the equipment go for a surge device. They do a great job of mimicing the wave action you feel on a reef. Tho they can get blocked up, fail and may overflow or worse.. A new design out there but still not for sale as far as I know is the Wave 2K. Great idea but many moving parts. more parts means better chance of failure.. And with a DSB you will get buildup of detrius and sand in the mechanism. The mechanisms inside that thing for the most part are nylon.. They will wear out fast with sand or crap rubbing in the threads.

I am gathering you want a constant flow in one direction for a specific period of time. then reverses itself. I think the best description of what you want to build is the closed loop circulation system I mentioned. One that alternates. That alone is a good system but to me adding in the random actions the powerheads or other devices add a bit more to the picture. To have that flow you fel in the ocean you would need to have the whole side of your tank as one huge outlet for a pump. Otherwise you will only get the flow you desire for the first few inches out of the outlet.. Then it is sent in all directions. Even then if you didn't have the same huge opening on the other side you woudl not get an even flow. You will get it coming into the tank from one 2 inch opening(assuming 2") and then exiting out another similar opening on the other side.. With that you won't get the flow you desire throughout the tank. For the most part only between the two outlets/intakes. If you have only that you will end up with areas where there is no circulation or turnover of the water. Dead ares in effect.

We are doing the best we can to re-create something we can't possibly provide. that massive water flow you feel on the reef.

IMHO...

[ 21 November 2001: Message edited by: DJ88 ]