Why do we assume a large return pump is needed?

[Herbert T. Kornfeld]

One thing I forgot to mention before was that running the chiller on a closed loop ( or better yet on a bypass loop on the closed loop...or loop within the loop) on the main tank is a much better option than running in inline with the sump return. Multiple reasons. Heat and safety are the main ones...I know we talked about it earlier in this thread...first few pages or so. First, if the power on the return pump goes out, the water level can go down to the point of running the chiller dry sometimes. Second, on a closed loop all that extra length of coil that the water has to run through in the chiller has less of an impact on head-pressure with a closed loop bypass than on the sump return. Sump return pumps have enough to deal with as is, putting a chiller on one just adds to the heat it will create in trying to get the job done...making more for the chiller to deal with. If the chiller in on the closed loop, it can be run via a bypass on the outlet end so that its restrictive piping has little effect on the throughput of the loop, and therefore lower the heat produced from back-pressure, as well as making sure the chiller never runs dry.

mobert,
One thing I like about halides is that it allows me to run the lights on a cycle that starts later in the day, after the hottest part of the day (mid afternoon). My halides come on at 5pm and stay on until 11pm...the other advantage of halides being able to get away with a 6-8 hour photo-period. This helps with heat alot.

 

[SeanT]

Interesting thread.
I am in the "more flow the better camp".
Get the crap out of the tank, over the drains and into the filter socks/skimmer as fast as possible for removal.
No reason to let it hang around rotting.

Sean

 

[mwood]

Interesting thread.
I am in the "more flow the better camp".
Get the crap out of the tank, over the drains and into the filter socks/skimmer as fast as possible for removal.
No reason to let it hang around rotting.

Sean

You have to weigh you decision though. The higher flow would be better for removing solids, but worse for getting the thinnest firm off the surface. Remember, the you have two types of crap. Solids, and nutrient in the water. The nutrients tend to collect at the surface and you want the highest concentration of these nutrients to go to the skimmer. If you have water racing in and out of the sump and or skimmer, are they really removed? Does the skimmer have a chance to remove all of them? Or are you simply recirculating them around the tank?

 

[SeanT]

The skimmer will never remove all of them.
The way my tank is setup, the only thing I am really concerned with is the heavier crud.

Let me ask you this.
Where did you read:

The nutrients tend to collect at the surface

Thanks,
Sean

 

[mwood]

Anthony Calfo speaks on this all the time. This concept is mentioned in his overflow and skimmer threads. Here is one quote from his skimmer thread, but there are better ones.

"That reminds me of the problem with HOB skimmers... their feed pump is drawing water from several inches below the surface of the tank. Wanna improve HOB skimmer performace? Raise the powerhead as close to the surface as you can. Its not as good as getting overflow water (better concentration of surface protein overflow water)... but it is a huge help."

He is always referencing the concentration of proteins at the surface of the water. Don't believe it? Just redirect all pumps away from the water surface and don't overflow any water into your sump for a week. If you do, you will have surface skum for sure. This is why most have used powerheads to disturb the surface water, but how much better to send it all into the skimmer.

Marcus

 

[SeanT]

I have heard Calfo say this before.
I was hoping for some actual literature to back it up.
I am not saying that I can't believe it...just that a lot of wives-tales in this hobby run rampant and I like to separate them.

Still. MO' FLOW!

Sean

 

[mwood]

Ahhh, you wish proof. You should not be denied. Do a water change and put 5 gallons of the old water in a bucket and let it sit. A scum or film should form.
Proof 2, run two skimmers. One that pulls from the surface, and another that pulls from 2 inches below. You will see a difference.
Proof 3, the fact that skimmers work! Skimmers work on the principle that nutrients accumulate around the air water surface. If this were not so, you are wasting a lot of electricity by just running the pointless thing.

Marcus

 

[Herbert T. Kornfeld]

mwood hit it right on the head with that last one...the nutrients that we are trying to skim out naturally build up at the water surface. The same process that proteins go through in a skimmer (oxidation) happens at the water surface, so running large amounts through the overflow tends to mix these proteins back into the water column and simply blow them back into the tank where they will have to try accumulating at the surface again (and might not get a chance to ever). Then we have to buy a skimmer that is much larger with increased dwell time and capacity to make up for a large sump throughput working against it.

Proof? Well, seafoam that washes up on the beach (nature's protein skimmer), the scum and oil that builds up on the water surface...and the simple chemistry of oxidation of proteins and lipids that causes them to be lighter than water.

I hear you on the detrious buildup thing Sean. That, along with refugium throughput being bottlenecked are the two things that a low flow overflow can work against. There are solutions however. They were both talked about earlier, but I'll restate the one for detrious...

Why not keep the overflow to just skim the surface, and set up some kind of detrious filter in-line with the closed loop or circulation powerheads? Its not as if the skimmer is going to pull out sediments or anything...it will either settle in the sump or need something mechanical like a sock to trap it. This can just as easily be done with a closed loop. Then the overflow can be left to pulling out proteins, and the mechanical filtration can be left to the detrious.

 

[get-r-done]

Guys

Thanks for the good input so far. I think that I am going to put in 3 bulkheads in the 3 open holes of the tank. Then under the tank put a ball valve to close each of them off separately. Then I can put in the single stand pipe and run some fresh water into the tank and try out the singl tube. I can then play around a bit with the GPH flow in the tank. If I need to, I could put the other stand tube into one of the 3 closed- off bulkheads and open that valve and see what the flow is then

I guess I just want to be sure that a single tube will handle 400-500 GPH without problems.

What do you think of this plan??

Also What kind of fitting would you suggest , slip fitting or threaded?

Jim

 

[get-r-done]

bump

 

[Herbert T. Kornfeld]

I like threaded better...more secure. The plan looks good otherwise.

 

[skyfireblaze]

I personally would go with threaded. But I don't think it really matters. Is a glued slip connection really less secure than a threaded one? I mean if you take out these pipes you're going to be taking the tank completely apart anyways, so what does it really matter if you have to redo the bulkheads (assuming glued slip)?

I cases where you've got a CL or something and you don't care if you've really got a water-tight connection within the tank, I prefer to have threaded connections outside the tank with slip inside the bulkhead. I'm primarily thinking about cases where you've got a spray bar or something attached within the tank (not glued onto the slip either). This way the spraybar can be easily removed for cleaning, and it'd be easy to undo the threaded conection to redo the plumbing if it was ever needed.

Just my thoughts, and afterall, what am I compared to the Reef General?

 

[Herbert T. Kornfeld]

I agree 100%. Its just easier to undo what youve done with a threaded fitting rather than a slip fitting.

 

[get-r-done]

Ok, I guess I'll go with threaded.

Sometimes I read in these posts that they leak a bit. Is there a trick to how tight to get them or how much teflon tape to use?

Jim

 

[chtan]

I just have a general comment ....I tend to agree about using less powerful pumps .... it still achieves the desired results .... I run 2 Ehiem 1260 equivalents or a total of 4800 liters per hour .... in total my total wattage for pumps is roughly 650 watts to run a 260 gallon tank .... and I do not use very powerful skimmers too ... just the equivalent of 2 turbo-flotor 1000s (just about 120 watts) and it works very well with my predominantly SPS tank at home ..... basically, I started with the European approach of pump specs and all and the tendency to size everything just nice with no excess .... but I do note the past 2 years a tendency even in my part of the world to over-spec on pumps .... its partly because we can easily get the Iwaki-copycats very cheap from china and many hobbyists do not realize in the long-run high wattage translate into high power bills.

 

[Herbert T. Kornfeld]

Thanks for your tank specs and input chtan.

get-r-done, teflon tape is all I ever use, works great. Sometimes on the bulkheads in general, around the gasket, I do get leaks. For this reason I use plumber's silicone grease all around the rubber to make sure it seals perfect. I used to use regular silicone as well...pretty much making the bulkhead permanent...works just as well.

 

[skyfireblaze]

HTK --

I'm assuming that the Eheim 1060 pump listed in the RC head loss calculator is equivalent to the 1260 pump. Can you verify this?

I'm looking for a pump that'd be just about right with ~4' of vertical head. Of course, I'm also going to be using a HOB so I guess I'll have to keep things moving a little faster than the 150 gph I'd really prefer. Think the 1260 is the right pump for me?

Yeah, that's the tank there on the left (and below in the sig ...)

 

[skyfireblaze]

When comparing the 1260 (1060) and the 1250 with the following inputs:

vertical head: 4'
90 deg : 2
45 deg : 2
ball valve : 1
unions : 1
pipe exits: 1
pipe entrance: 1
pipe dia : 0.75"

I get that the 1250 would provide 187 gph while the 1260 would give 355 gph. I don't know, maybe the HOB would be okay with the 187 gph? But then again, maybe it's better not to risk going that low, eh?

 

[NoSchwag]

I have an eheim 1250 and I cant seem to get everything over the top of the overflow.. It's very important that I get everything over the overflow because I am running a BB SPS tank.

I have my penductors, on 6" segments of loc-line, running on a pcx-55 (pressure rated pump) pointed PERFECTLY. They point straight down the back of the inside corner of the overflow (old style aga 120). The water goes down the back, across the bottom diagonally, meets with the flow from the other side of the tank in the middle front, up the middle of the front, and DIRECTLY back to the overflow.

It's obvious that it's perfect because not only can I see all of the particles in the tank slam into the top of the overflow, but if I drop in one of those floating thermometers anywhere in the tank, it shoots directly back to either overflow. Also the water on the top ripples.

Don't get me wrong it's a great pump, but I think I will be replacing my 1250 with a 1260.

My question is will a 1260 be a good pump to feed my overflow directly to a skimmer with a 900 gallon recirc. pump??

 

[Herbert T. Kornfeld]

Sorry, was busy getting banned for a week...lol. What was that again?