River tank manifold

[Sandra]

Hi

I have finally taken the plunge and bought a new tank for my hillstreams. They are currently living in one of my old tanks which is too short, wide and high for a river tank, although they seem to be doing really well with a bit of a make shift setup.

I only have room for a 1.2m tank, so it isn't going to be an overly large river tank. I'm going to build a river tank manifold and have been giving the design some thought.

I want to get as much flow as possible out of my power heads, so I would like to reduce the number of corner and T pieces in the manifold.

Is there any reason why the power heads and sponges have to be on one inter-connected manifold? Could I use 3 long lengths of pipe with a corner piece at each end to turn up to the sponge or power head? I would end up with a sponge connected to a power head on a long piece of pipe with only 2 corners. I would then attach these to some acrylic strips (running from front to back of the tank) to help the 3 pipes sit in place at the bottom of the tank.

As I have never run this sort of setup before, I am not sure if there is an obvious disadvantage to having each sponge and power head on it's own network so to speak, rather than having them all interconnected.

Any thoughts or advice from those who have been doing this for years? You could save me having to take it all out and disturb my little hillies after a couple of months when I realise a flaw in my plan which I can't see at the moment.

15 assorted hillstreams are asking you to help me get it right first time.

Thanks Sandra

[Mark in Vancouver]

Congratulations on your assimilation to river tanks! I don't believe that corner or t-joints significantly reduce flow. Part of the advantage of having one solid manifold is stability... It forms a kind of frame under the substrate, and both the intake and outflow ends become very stable and rigid.

I think the size (strength) of your powerheads has the greatest impact on the rate of flow.

I'm sure others will weigh in on the issue.

[crazy loaches]

Is there a reason you want to not interconnect the manifold pieces? Its just an easy way to build it and make it rigid. I just dont se an advantage of doing it a different way. The other thing I see is if one filter got clogged you'd still have the other ones. If each had its own filter then if one got clogged it would strain that powerhead. I've never dont a river tank (yet ) so these are just observations. Good luck!

[Graeme McKellar]

Hi Sandra, Mark is correct that flow would not be affected much by a few tee's and elbows .Martins design is a "suction manifold" that moves the pump intakes to the other end of the tank There will be a negative pressure in the manifold caused by the pump pulling the water through it.The major cause of reduced flow will be the sponge filters . If they are not large enough or there is not enough of them for the pumps to suck the required water then flow will reduce markedly. Flow also reduces as they become dirty and clogged. Flow of the pumps will always be reduced by the sponges but having more and larger sponges will help as will regular cleaning. The only other thing that can reduce flow is the size of the piping - suction piping should be larger than the outlet of the pump.
Martin's design is just so functional there is really no need to improve it.
Good luck with it all - Im know your Hilleys will love it. Graeme.

[Diana]

I also will suggest you interconnect them for stability.
I am using something of a manifold in the tanks for a similar purpose, but when I need to remove, clean and replace a sponge the whole manifold gets dislodged.
A one-piece unit, criss-crossed in a few places and with the large rocks and such of a river tank sitting on the pipes would add a lot of stability to the set up.

While an engineer might find a difference in the flow (single line vs cross-connected) I think the difference would be minor, and more than made up for in the back up/redundancy factor: If one sponge tends to get clogged faster than the others, then the cross-connections will still permit all the powerheads to get the water they need.

[jones57742]

While an engineer might find a difference in the flow (single line vs cross-connected) I think the difference would be minor, and more than made up for in the back up/redundancy factor: If one sponge tends to get clogged faster than the others, then the cross-connections will still permit all the powerheads to get the water they need.

Folks:

I hope that yall will find to following discourse interesting.

The "high end" filtration systems for the nicer golf courses (which due to cost typically use raw water and not potable water) are designed virtually identical to the "manifolding discussed in the thread" and for many of the same reasons.

The raw water transfer pumps are manifolded into a header;
the header discharges into many sand filters which are placed "in parallel";
this sand filters discharge into a 2nd header;
the 2nd header discharges into the center of several cylinders which contain very fine wire mesh cylinders;
the flow from the cylinders is discharged at the cylindrical walls and this discharge flows into a sump;
the high head pumps (which cause the irrigation heads to function) are manifolded on the intake side as well as the discharge side.

For an 18 hole course there are typically 3 transfer pumps and 3 high head discharge pumps. When the course is being irrigated 2 of each of two types of pumps will be active with the third idle with the pumps being rotated each time the irrigation starts anew.


Four Additional Items

One

All of this filtering, manifolding, etc may seem like overkill.
The construction cost of a typical nice 18 hole golf course is in the $4M range of which very roughly 40% is due to the installation of the irrigation system and turf.

Even very fine particulate material will eventually "silt up" the irrigation heads. The silt is "hardened" when the head is noted to have it's capacity reduced, cleaning the head is not possible and a new head must be installed.

Other deleterious materials can cause even much faster problems and I will use snails for an example as I am intimately familiar here.
These "little devils" are virtually invisible to the naked eye but after only a few weeks of not "being filtered out" they will be on the walls of the transmission mains, clogging up the small pipes which transfer the water to the irrigation heads and have clogged up many irrigation heads.
(Please do not ask how these "little devils" can live and affix themselves to the walls of a pipe in which the velocity is in excess of 5 feet/second as I do not have a clue.)

Two

Typically a small chemical pump discharges minor amounts of chlorine into the sump for disinfection and chemical filtration.

The chlorine concentration and detention time in the sump is small (ie. the water which irrigates the golf course is not potable).


Three

Believe it or not the effluent from a domestic waste water treatment plant which employs tertiary treatment* is of much better water quality than typical raw water quality.

The pumping, manifolding and filtration processes are not reduced.

The sump is greatly enlarged (and/or for those yall who live where it actually rains every now and then a lined pond is constructed) and the chlorine pump is no longer small. "The theory here" is discharge water on the golf course which is near potable via the addition of more chlorine as well as a longer chlorine contact time prior to the discharge pumps.


Four

The golf course filtration systems include one item which I have not "figured out" how to implement in an aquarium environment and that is filter back flushing.

This flushing is accomplished via a high head pump the inflow of which is the from the sump and outflow of which is to the header into which the micron screens discharge.


I hope that "I have not put everyone to sleep here" but as I indicated earlier I thought that some folks might be interested in this discourse.

TR

[Sandra]

Thanks everyone

I know that in a central heating system a corner slows the water flow the equiv of an additional 3 foot of pipe. I think T's cause a similar disruption to the flow. At least a central heating system doesn't have snails to contend with, unlike river tanks and golf courses.

I am going to be constructing my manifold this afternoon. It is going to be like being a kid again with a macarno set! (Showing my age!)

Thanks Sandra

[crazy loaches]

The T's shouldnt cause as much restriction as an elbow, the elbow has such head loss due to the fact that its a very short radius 90* turn (which is one reason on my current tank's plumbing I used long radius elbows, to help the flow a little). Unless a lot of water was flowing through the corner of the tee, the only real loss will be some loss due to turbulence through the fitting, but I wouldnt worry too much about it. Good luck with your project.

[Martin Thoene]

Well here I am on my Birthday and my babies are being built all over the shop

I think others have recognized the simplicity of my design and it's inherant stability and flow diversionary advantages in event of a blockage.

I basically designed it with car exhaust systems in mind and having some kind of balancing cross-pipe was always a design consideration plus it gives something else to plonk a nice rock on top of to fix the whole thing in position.

Martin.

[Tinman]

The manifold may also be used with a intake pipe across the sponge end, with a series of holes drilled in it and no sponges at all so as to just increase flow and never be affected by the sponges clogging .Then use a cannister or two for a filter. This reduces the cloud created by removal of the dirty sponge....and the appearence of the sponges at one end of your tank.It will not keep fry from being drawn in but does work well in tanks not designed for babies to appear....I find sponges a PIA at times slowly getting plugged until you clean . No sponges gives a more constant flow over the long term but does not add to filtration . I personally keep most filtration outside the tank for cleaning purposes which is different than many......This will not work if ya want babies as they can be drawn in. and can not feed on the filter which is an advantage of having one in a tank that I clearly see.

[jones57742]

Sandra:

I am very glad that crazy loaches posted as I got way into an example which I believed might interest folks but not into the details.


Engineering Details


One

The head loss through pipes/tubes is (in reasonable ranges) very roughly proportional to the square of the velocity multiplied by 1/2 the length of the tube.

The head loss for 10' of pipe which is delivering 10GPM and inside diameter of which is 1" the head loss is 0.9 feet (0.4 PSI)
For a 1/2" pipe the head loss is 24.7 feet (10.7 PSI).


Two

As important as the values set forth in One above is the velocity.

The velocity in the 1" pipe is 4.1 feet/second.

The velocity in the 1/2" pipe is 16.3 feet/second.


Three

The reason the velocity is important in a fish keeping environment is that a minimum velocity is necessary to maintain "scouring" of pipes (ie. no large microscopic deleterious materials, algae, etc).

Velocities significantly in excess of the minimum velocity will result in significantly decreased pump life and as well as increases in electricity bills.

I have done "a ton of hunting for literature with respect to this issue" with no joy.

I do know that 3 feet/second "will not work" as the tubing from my pump to the jets in the tank have serious brown algae.

If I were setting up the manifold I would use 6 feet/second for the piping size (in the engineering world when no information is available this velocity is always my best guess).


Four

crazy loaches is correct in his post as fittings do add to the head loss through a piping system.

I have calculated the following for your inspection (based upon the pipe sizes and flow set forth above) [feet is feet of head loss and feet of tubing].

Tee - Straight Outflow
1" Pipe - 0.1 feet
1/2" Pipe - 2.2 feet

Tee - Orthogonal Outflow
1" Pipe - 0.4 feet
1/2" Pipe - 6.8 feet

AND for the long sweep bend which crazy loaches quoted
1" Pipe - 0.2 feet
1/2" Pipe - 5.1 feet

Sandra and folks I hope that I did not overload with the above but engineering is typically empirical (and therefore seemingly complicated) whereas physics is simplistic.
(ie. The main concept in hydraulics is based on upon the conservation of energy which is very, very simple in physics but empirical determinations induce a "bunch of what has been termed hard to understand")

TR


BTW:

No one seemed to be interested in my "golf course analogy" but if anyone is interested in understanding the hydraulics associated with our aquarium filtration system please advise me and I will generate a thread (least I can do as nice as you folks have been to me).

[Diana]

So... Lets say you built a manifold that had 3 sponges that dropped down to 3 tees. Then there were 1 tee and 2 -90* changing the flow to horizontal. pipe x 3 pieces @ 4' long then 2 more 90*s and a tee to connect the other end of the manifold together, then add 3 tees to turn the flow up and into 3 PH.
Simplify it: Water enters one sponge, changes direction in one tee, changes direction again in either a tee or a 90 (either way making a 90 degree turn) then another tee or 90, and another tee. Lets just say they were all tees, no 90s (since you posted flow loss for tees) Water passes through 4' of straight pipe, and easily another 1' of pipe connected by the fittings. 5' total pipe, 4 tees.
In 1" pipe the loss to each tee is .4 feet, the loss to the pipe (5' of it) is .45 feet. Total loss is close to 2 feet. This seems to be very little. The sponges, partially plugged will likely cause more loss.
In 1/2" pipe the loss to each tee is 6.8 feet, to the pipe (5' again) is 12.35. Total loss is close to 40 feet. This seems more significant, but how much flow can you get out of 1/2" pipe? How much loss is this, really?

How do these losses get translated to GPM?

And it still does not answer the original question: Is it better to run each sponge-to-powerhead portion separately, or to cross connect them?

In the example above I probably made the manifold more complex than it needs to be.

The simplest cross connection would be tees with the water simply passing through them, no change of direction.

[crazy loaches]

Jones, you do like to show the details, I know this from aquariacentral

I am curious though, one thing you mention about the head loss through the long sweep bend (I assume 90*) there isnt a comparison to a straight cut 90* bend (or whatever the actual name of that is called). I've never looked up the data, just assumed the longer radius bends are better for flow than the ones that arent 'radiused' at all. Not sure if things like that are even available for smaller plumbing that river tank manifolds would use, just something like the 1.5"-2" plumbing I used in my 240g. Where possible I used wyes or long radius wyes instead of plain tees. And double wyes instead of crosses.

How do these losses get translated to GPM?

Once you know the head loss you need to refer to the pumps specifications, most should include a chart graphing flow vs head. However for the powerheads used in river tanks I dont know if they are rated like this, I've never happened to see charts on powerheads, but they are common for pumps. I am also not sure if the loss being on the intake side would work the same exactly, since they flow test based on the loss being on the outflow side.

[jones57742]

Diana:

How do these losses get translated to GPM?

As crazy loaches indicated the translation is via the specifics of the pump which can be ascertained from the discharge/head loss curve for the pump.

Having said that 40 feet of head loss "is way, way more than a bunch" in an aquarium environment.

As an example my Iwaki pump (the 30 RXT type) works just fine for my 110G tank and provides approximately 15GPM flow with approximately 5 feet of head loss (Static Head Loss[dimension from the pump to the water surface] plus Dynamic Head Loss [losses through pipes, fittings, etc]).

At 15 feet of head loss this pump will not discharge any water and would soon become a crispy critter.

Please refer to
http://www.marineandreef.com/products/I ... D30RLT.jpg
for an example of a pump curve.

And it still does not answer the original question: Is it better to run each sponge-to-powerhead portion separately, or to cross connect them?

IMHO and per the example in my first post manifolding is the best option.


crazy loaches:

For the pipe sizes which you quoted a sweep bend is approximately twice as efficient as a standard bend.

TR

[Graeme McKellar]

Hi All. There is no "head-loss" in this system as the water is discharged at the same height as the impellor and there is no "suction head-loss" because the water is drawn at the same height as the impellor. There is only loss of flow due to adding the sponge filters as all filters reduce flow. My canister pumps 950 LPH with no filtration and as soon as filtration is added it reduces to 780LPH. Ifyou want full flow do what Tinman said and use a inlet manifold with lots of small holes in it. By using larger suction piping than the pump outlet will provide a safety factor that will eliminate any loss through bends or tees . eg 25mm outlet 32mm inlet. If you have 2 pumps and 3 sponges (or more) it will lengthen the time between cleans.
There is only one addition I will add to mine thats a vaccum guage that will tell you when cleaning is necessary due to the increase in vaccum as the filters block. Cheers Graeme.