"Remote Intake" part 1

[Tanker]

I have been tossing this idea around for quite some time, and being fairly handy I felt the time had come to finally put it all together...

Of to Rona and tada... let's see what happens. The goal is to move the intake of a standard AC Mini HOB to the other side of the tank.

Why? Well, from what I have seen, HOBs tend to only move the water in one half of the tank, rather than provide any sort of current or flow throughout the tank. By sucking from one side, and blowing on the other... well, form follows function.

I have 'charted' out what I have seen for flow in the tank via the really poorly drawn diagrams below. The hideous purple shows the normal intake of an AC Mini sitting towards the left side, and the bigger the arrows, the bigger the flow.

The lower picture is what I "hope" happens... any flaws to my plan? It's basically two brass 90 elbows, and some 5/8" id clear tubing. The old intake screen from the AC is modded to fit over the intake. Everything runs on the back of the tank, and aquascaping will essentially hide every single bit of it.

Now.. the only flaw I have thought of is that I am creating a 'head' that the AC will not pull up on... but at the same time, logic tells me that the siphon effect caused by the RELATIVE height of all pieces should negate this, entirely. The new intake is only about 1" lower in the water than if the filter was connected as usual. Will there be a discernible drag created by the water flowing through 30 inches of additional hose?

Everything is cut out and fit, but as I purchased a 10 foot roll of the tubing, I was unable to get it mocked up tonight... the tubing is being straightened out tonight, so I may have proper pictures to illustrate tomorrow...

Am I going to make a mess? Burn out an AC? Or revolutionize the HOB world?

[dunl]

If going across the width of the tank, I would keep the intake as low as possible, so that you do not feed the intake directly from the outflow of the filter.

If the filter hangs on the end of the tank, and the intake is way over at the other side, it should work fairly decent.

You could always take an empty tank, get the filter all set up and going and then stop it briefly, add food colouring to the filter, and do a quick check to see how the flow works. Some other type of slower dye might work better, but it would have to be non-toxic, or on a junk tank and filter you don't plan on using....

[RD.]

Will there be a discernible drag created by the water flowing through 30 inches of additional hose?

Yes, I would think so. I suspect your GPH rating will drop by a few notches.

[dunl]

Wouldn't the pressure in the hose be the same throughout, at the same height on both sides of the tank?

[Tanker]

I know there will be 'some' drag... physics says so, and there are a ton of calculators on the web to figure it out with, but they all use terms I am not familiar with as my practical use of hydrolics is fairly limited (lol understatement!).

Using the best estimates I can gather, I have found an expected psi drop from 0.2 to 2.2 depending on the site and the complexity of the calculator. These are typically geared towards finding drop caused by the rough walls of steel pipe, and the head of the pump... I am using much smoother vinyl tubing.

I guess the sunny side is this filter is going to be running a 14 gallon tank, which is about 10 gallons of actual water... a little AC mini with even 50% loss will do just fine, as there will only be two fish in it. :thumbs:

I guess there is nothing else to do but actually hook it up, and see?!?! ANyone else have an idea? I will not be putting it together until Wednesday night with LOTS of pictures (just in case it actually works).

[RD.]

Why not simply run two AC mini's, one towards each end of the tank?

Not only will that solve your problem of water movement, but it will also provide a back up filter in case one of them breaks down while you're away from home.

Edited August 10, 2005 by RD.

[African_Fever]

I'd think in a tank as small as 14 gallons that water flow wouldn't really be a problem (due to the small size of the tank). Why not just add a normal extension to your AC mini and keep your water level higher? (I've found that with a high water level the out flow of AC's is more across the surface and spread out than down). Seems like a lot of work to go through for a tank that small (but something to consider if you were running say an AC 500/110 on a 33 or 48/55).

[Tanker]

80% of this mod is for looks, 10% is for funky value and 10% is to prove to myself that I can make a better mousetrap.

Really... all I am doing is making a HOB canister... sortof. Tonight I'll get it hooked up, and I will get some food coloring to test it out with... SO happy I don't pay for water.

Here is a question...

Can I make the intake vertical runner on the right side higher, thereby making a 'skimmer'?? As long as the water level is high enough to always allow flow into the tube, would that not work?? The intake tube would be 11-12" long, to allow air bubbles to rise up towards the grating, should any be caught in there... no reason the impeller would ever get air, unless the water level dropped below the intake grate itself. Shutting down the filter at water change time and making sure the level is topped up should negate problems. The only drawback I can see would be the sucking sound...

I'll set it up tonight with both ways and see what happens! An HOB skimmer stealth mod... super cool! (if it works...)

[Big Red 265.]

It has been my experience, playing with the plumming on a Fluval 404, that the elbows you are using will hurt your GPH the most. The extra tubing is really not a factor because your not drawing the water any higher from the surface than you were before the mod. It is the ID (inside diameter) of the elbow that hurts.

Let us know how it goes

[DCallele]

I have to agree with Big Red, it is the elbows that will hurt the most - you are fighting with the momentum of the water as it is forced to change directions which causes a lot of energy loss. After that, inside diameter modifies things like the type of 'flow' that you get, etc..

I've modded AC300s and 500s with a length of clear vinyl tubing to improve the water flow as you have described. There was a small loss in flow but it does work much better, imho, than just the straight intake below the water return and has less loss than the elbows. Kind of ugly to look at though :P

That said, I don't do it any more because my tanks are always in such a state of uproar but I did like it when they were more stable and definitely recommend it.

WRT the skimmer action, I found that the water levels were really picky unless you develop some kind of a floating overflow as is used in the commercial version.

If you come up with a good idea for a floating skimmer, please share it with us.

Good luck!

David

[Rainmaker69]

After you get the mock-up made and tested, don't forget to unplug it to test if it will still self prime. A filter, or any pump for that matter will push water a lot further than they will suck it. Your elbows could be the deciding factor in that respect.

[Tanker]

Well, 24 hours of testing, and it's a thing of beauty...

I started off plumbing it in, and figuring out how to get curved tubing straight and finally gave up and worked with the curves... they'll either straighten out themselves, or be replaced by thinner walled tubing at a later date. Got it full of water, fired up the filter and off it went... took a LONG time to get the air bubbles that were sticking to the side of the tubing out, but I could see the water flow literally tearing the bubbles off the inner walls with the flow that was in there.

Compared to an identical filter running in the adjacent tank, I'd say this one is sitting at about 75% flow... not bad when you consider all the factors. That will still run the entire volume of water about 7 or 8 times an hour, which is plenty for me... afterall, there will only be two Figure 8 puffers in it, so the bioload will be essentially nothing.

The tip of the intake screen (stock AC) is out of the water about 1/8", which leaves the best part of 2" that the water level can fall before the intake goes dry. And should the water level fall lower than that, the filter cannot possibly suck hard enough to force air to go down to the bottom of the tank (I tested this by running the system for one hour, then draining 8 of the 13 gallons of water out of the tank and running it like that for four hours.) The filter ceased to pump as there was no water to inhale, but the system never drew in air, instead it would just sit idle. I checked the temp of the water in the filter itself after the four hours... the constant motion of the impeller in an idle pool raised the temp of the filter water by 1 degree. Considering there was no media in the filter at this time, I have to assume that an overnight situation would obviously affect it more, as there would be less water to buffer the temperature, and a longer time frame. But the initial results are quite promising.

When the tank is re-filled with water the intake tube is not flooded with water, and doesn't allow any air to enter the horizontal portion of the system, instead a vortex kind of action is observed as the water simply flows into the intake tube and pushes the air back out the top of the intake screen. This is where the skimmer application is at it's finest. Just stopping the tank filling for a few minutes with the water level 1/4" over the lowest part of the intake screen and wild surface motion could be observed as the water was drawn into a veritable whirlpool drain. Topping the tank up to it's "full" line doesn't stop the whirlpool effect, instead it slowly (over the course of about 3 more hours) will eventually fill faster than it drains, and the water's surface motion returns to a more leisurely pace.

In general, I am very happy with the results of this trial. Next time I'll hunt about for better elbows (the id of the ones I used were the same id as the normal piping on an AC, but were a VERY 90 degree elbow... something meant for plumbing applications specifically might be more suited... mandrel bent 3/4" brass tubing? :rofl: ) but given the relative low cost of the parts I used and the results I have received initially I will certainly be improving on the system in the future.

Costs?

AC Mini - used $5

Tubing - 7/8"odx5/8"id clear tubing, 3 ft @ .70 per foot = $2.10

3/4" brass barbed elbow, 2 @ 1.47 = 2.94

Even with tax, under $11... and with the right plants it will be nearly invisible.

Empty

And full

There will be some more plants added in, once it's cycled. The zon and cabomba is just tossed in there for now to get a feel for it. The entire back wall of the tank will be covered in plants once it's grown out. Nice thing, as it will hide the HUGE suction cup I had to use as weaker ones simply pulled away from the glass.

More will be posted on my blog in an article once I get some time next week. Additional pictures, plus more testing as I come up with ways to really stress it.