My LFS told me to keep my rock off the back of my tank 3 -4 inches for proper water circulation. Is this something that is typical in a reef tank? All the tanks I've viewed online appear to have their rock stacked against the back.

Also, I have 2 - Tunze Nano-stream powerheads and a Tunze 730 Multi-controller. My tank is an Oceanic Staphire Tek 120g. Do I need more than 2 powerheads for my tank. I plan on putting softies, LPS and MAYBE some SPS one day.

It has 4 adjustable supply nozzles that protrude out from the back. Should these be pointing in any particular direction so they don't interupt the "flow" of my 2 powerheads on each side of the tank?

My LFS said to eliminate "dead zones" but I don't know if that means to make sure the current is strong enough ANYWHERE in the tank to move an object about the tank or if it means something else.

Thank you in advance for helping me with my multiple questions.

John:o

I have had MANY tanks set up since beginning the hobby. In the beginning, I'd stack rock any which way I liked. I ALWAYS had circulation problems. I now keep my rock off of the sand, by way of PVC stands, and at least 1 inch away from any glass. Not only does it promote better circulation, but it helps when cleaning the glass of algae. I'd agree here that your LFS gave GOOD advice.

The Nano Streams are EACH pumping about 1,190 GPH. In a 120, this is about a 20X turnover rate of internal flow. You mentioned the 4 return nozzles, but didn't tell us what kind of pump is returning said flow. You would want to include the "gallons per hour" of that pump, minus any head loss, in your equation.

Personally, I think you'd have some problems with flow that is too low. Granted, you aren't into SPS yet (which LOVE high flow), but even with LPS, softies etc. you would probably have a problem with detritus settling, and causing algae blooms or water problems. I have a 50X turnover in my little 38 gallon system. Some folks have gone into the hundred + of gallons per hour in flow rate.

What is more important, is area coverage (this is what Mr. LFS meant by "dead zones"). If you have this 20X turnover rate, and the pumps are moving water in the MAJORITY of area in your system, you COULD be okay. If, however, you have a lot of live rock in there, and the power heads and/or return nozzles don't provide adequate coverage, you will have dead spots in flow, and therefore, sessile inverts in that area(s) will suffer. You will also find that this is where all the detritus will pile up. Remember, the goal of flow is to rid the sessile inverts of waste, since they depend on the water to do so. Another goal is to keep the detritus and other impurities in the water column, so it can be taken into the sump, skimmer etc. to be removed.

When using the controller, you really want to ensure that the "switching" doesn't happen fast. You want the pumps to push as much water to reach the capable "fetch". What I mean is, if you have a pump that pushes 1,190 GPH, but it switches off after three seconds, you didn't give the pump enough time to "stream" as far as it could. Therefore, you are going to have dead flow in areas where the water stream stopped before the pump reached it's full capability.

One of the benefits of using products like B-Ionics and other supplements that "cloud" water for a short time, is that when you introduce it to the system, you can track the flow of water. If I add any supplements like this, I watch the flow pattern, marked by the chalky white water. IF I see areas that don't get the "white wave", I adjust pumps accordingly. This is just a tip for users of said products. I'D NOT add it for this experiment, unless you need it.

Dave

Dave,

Thanks for the fantastic advice. My main pump is approx 980gph rated, with about 4' head ht. So it's obviously pumping less than that. I could purchase two additional powerheads to help with the flow, but i'll see how the flow is really working once i have my lights on and can see where 'things" are settling.

Also, i don't think i can get my rock off the sand because i have some large pieces and it would be extremely difficult to pick them up. I had to have two people put them in. So i don't know if that will be an issue long term. But i will definitely keep the rocks off the back.

Here's my current setup...

http://i262.photobucket.com/albums/ii101/john_waggs/tank008.jpg

What is the return pipe/hose inside diameter? What is the pump brand? I'll get this flow down for ya ;)

Forget it.. I'm assuming it is a "Quiet One" because it has the same rating. So, with that said... with 4' vertical loss and an assumed diameter of 3/4 return, 4 nozzles..you'd haveTotal losses of 8.28 feet of head pressure, or 3.58 PSI. with a flow rate of 695 GPH in the end. If your diameter plumb is 1 inch... Total losses are 6.08 feet of head pressure, or 2.63 PSI. with a flow rate of 803 GPH.

So, add that to the total GPH of the tunze's and divide by volume and you have a decent bench mark for flow rate.

i fixed your link, it was missing [ at the beginning.

My pump pushes water through 1 1/4 pvc then branches off to the 2 suppy feeds. I've attached a picture.
http://i262.photobucket.com/albums/ii101/john_waggs/120sumpphoto.jpg

holy spaghetti... okay... didn't take into consideration ANY of the 90's, balls, etc. Lemme try this again...

Really...that's 1 and 1/4? Are the feeds after the split also 1 and 1/4?

Total losses are 3.73 feet of head pressure, or 1.61 PSI. with a flow rate of 772 GPH.

After the split it remains 1 1/4 OD for about 2 inches then it is forced to go to 1" for the 2 feeds that came with the tank.

I thought I made the piping pretty efficient and still allows me to access my sump and protein skimmer (not shown since it's noisy as all hell, but that's a different thread). Would you have run the piping any different from the pump to the feeds?

My pump is a Pan World NH50PX - X model.

Yer plumbing is a work of art my friend... I was just surprised to see the forethought and details. Most people just "rough it in".

Good work.

Dave

I have a small powerhead in the back of my tank about 2/3 of the way down, behind the rocks. It is on a timer and runs at night to help prevent detritus building up behind my rockwork.

Make sure you can get your cleaner magnet between the rocks and glass. I like to also be able to get my scraper between the rocks and glass.

Why is it on a timer?

Does it stur up the sand bed at all?

My two PH's are also at the rear but mounted on the sides at the upper right and left. One points directly across the tank to the other side. The other one points from the rear left corner to the front right corner.

Again, I have nothing in the tank but LR and some decaying shrimp, which were used to complete my cycling. They had drifted to areas between my rocks and settle there. Which makes me think I don't have any water flow in those areas.

I just don't know if I need more PH's or not, those Tunze's are very expensive.

Thanks for your comments.

Johnno, welcome to the party bud!


Timers to counter linera flow patterns & only active during peak times as to not blow her fish from their sleepy cribs . far off carmie> ?

It is a 100 gph powerhead so pretty low flow. I have it aimed so it blows the sand a bit but does not dig holes in it. It is crossing the other flow and since it originates from lower in the tank mixes up the pattern. Actually V, my thinking was the opposite, that by running it after lights out it would get the detritus into the water column and feed my corals. Do you think I should switch it?

the differences are what makes this world great!