Pond Boss Forums AERATION Systems questions Anyone had experience with these pumps?

http://www.ebay.com/itm/DC-12V-160L-Min-...-/151800129843?

Hate to jump to imported, probably throw-away if breaks, but hard to beat price for output ($133; I calculate just over 5 CFM and max 17 PSI)

Not finding many gast pumps on EBay everyone is talking about, and I will be off grid/solar/tentatively DC power source

Have had no experience with them. However have had experience with 115v linear compressors.

Something worth asking the seller. Are rebuild kits available? And at what cost? And what shipping will be for the kits.

The reason being, my experience to date indicates a diaphragm for the pumps I use lasts about a total run time of about a year continuous. If kits are available and reasonable, they can be easily rebuilt. If not, they are throwaway.

The pumps I use have rebuild kits available and takes anywhere from 15 minutes to an hour to rebuild (depending if a person has previously done it and how fast/slow (I like to refer to it as methodical) you are. Shipping on a single kit is often more than the kit itself costs. But I have found a place that is about half price of most places for the kit itself (less than $10 per kit) and by ordering three or four at a time the shipping doesn't get excessive (costs same total to ship one or multiple kits).

Just something to think about. Diaphragm type pumps with rubber components are eventually going to get brittle and the diaphragm split.

Your link didn't work for me.

Something to consider: I have 115 volt AC outdoor air pumps that are designed for septic tank aeration and work very well for me for my indoor systems. I used one sucessfully for shallow winter aeration two years ago until temps dropped into the single digits. Then the rubber diaphragms apparently got so stiff the pump stopped working, as when I brought the pump back inside and it warmed back up it was fine.

The pumps are sold as linear air pumps but in reality I think they are technically diaphragm pumps.


http://www.bluewaterpumps.com/

Cecil, my pumps are diaphragm driven by a linear type motor. In other words the armature moves back and forth like a solenoid would and this linear motion drives the diaphragm back and forth.

It appears in his link (worked for me) that the DC motors are a conventional rotary electric motor with some sort of crankshaft or cam mechanism that drives the diaphragm to make it pump.

I don't know of any way to make a linear motor out of DC other than to have an electronic circuit to transform the DC into some form of AC.

But in both cases, it is a diaphragm that pumps the air. The difference being either a rotary electric motor or a linear reciprocal shaft motor.

Thanks for the opinions, guys.

Link from what looks like the manufacturer:

http://www.boyuaquarium.com/en_ArticleShow.asp?ArticleID=2052

I called Bluewater, they only have AC pumps. And for a pump with comparable stats (150 L/min, 0.15 bar) it is $390, $80 rebuild kit. Curious that they have a model just below, 120 L/Min, 0.15 bar, for $195, same $80 rebuild kit, which I'd probably buy if it were DC

That cost of $133 on eBay (160 L/min, 0.12 bar; seller has good positive stats) is with shipping

Just an FYI, diaphragm type pumps have a performance curve that drops off significantly with back pressure. In other words, 160 lpm likely is the output at 0 psi. At the rated stall pressure psi the output is likely zero lpm. At pressures in between the flow in lpm (or cfm) will be intermediate. I have not looked at your second link yet, but if they have a performance curve (or can email or otherwise provide one) it is very useful information. For example, say you want to run your diffusers at 8' depth. That is about a 4 psi back pressure to the pump. So the pump output at that depth/pressure might only be 80 lpm instead of the advertised 160 lpm. If you can source a performance curve chart on the pump, you can see what the pump will put out for flow at the depth you want to run it. This will give you a lot better idea of the properly sized diffuser(s) to use.

Makes sense. You definitely know more about it than I do.

I have emailed them to ask for a performance chart.

Are there any generalizations about performance curves for diaphragm air pumps? wondering if I can't get one, if I can approximate from others' data. I realize you may have just been throwing out numbers, but if max pressure is 17 psi, and I'd be operating at 4 psi (likely - I have to measure, but I'm thinking about 8 feet depth) and have half the output, does performance tend to drop off exponentially, or does it tend to be more linear? (i.e. 8 feet may see at 25-30% drop?)

For an example this is the performance chart for a Hakko HK100 linear air compressor chart. It is rated at 100 lpm. It might or might not be similar to the curve of the pump you are considering. If the DC pump uses a crankshaft to drive the diaphragm, it might have a flatter performance curve with less output drop as pressure increases compared to a linear type motor. I just don't know. Just trying to envision in my minds eye how the crankshaft might keep the stroke of the pump consistent where on a linear motor with the shaft going back and forth the stroke will shorten as the back pressure increases. But, again, "I don't know".

http://www.hakkoairpumps.com/UserFiles/HakkoHK100LGraph.jpg

Notice also on the Hakko pump that the 100 lpm is at about 5 psi. It actually puts out about 120 lpm at 0 psi. So that is another bugger when it comes to figuring out pump output. One company might rate at 0 psi, another at 5 psi and another at yet something different. That is one thing I hate about the Pondmaster (cheap Chinese) pumps I use. They tell nothing other than give an output rating, but no information about it. A good high school senior in shop class with a pressure gauge and a flow meter along with an Excel spreadsheet could create a flow chart in about an hour. Yet some of these MFG's don't seem to think they need one.

Here is an old thread I was involved in that might have some useful information about depth vs pressure, etc.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Main=27741&Number=354891#Post354891

Regarding the initial air inflator pump, I suspect it is not designed to run continuous. Thus its life span is likely to be short when used for pond aeration. Be prepared.

Ask Rex. I think he used them for intermittent hauling. It was the red colored flavor of the same gizmo tho.

Somewhere on U-tube there is a video of a guy who creates a solar powered pond aeration system. I don't think he is a PBF member. I have linked to it before but if a person does a utube search for solar pond aeration I think it will come up.

As I recall from his experimental process, he initially uses a DC pump he got off ebay. May or may not be same type of pump. But in the end he gives up on the DC for lack of pump reliability. He eventually goes to a battery, inverter, and linear type AC compressor which he seems to be happy with in the end.

If a person is interested in that series of videos, I'm sure a search will bring it up.

Edit: I found the guy that made the video with later stuff but I don't see the original where he was using the 12v DC pump that failed. So he may have decided to take that one down.

It is amazing how much bad information there is out there on ponds and aeration. But if a person picks and chooses what he watches, there is also some stuff worth considering.

The motor shown in the link is "Mag Drive". As far as I know, all mag drive units are continuous duty since motion/resistance friction heat is not in the equation (or extremely minor, and only at the bushings/bearings holding the magnetic shaft in alignment). I dangerously "assume" the motor design already has provisions for removing the electrical and magnetic heat energy generated. The electro-magnets/permanent magnets will or won't create a field strong enough to move the magnetic shaft at a given motion resistance, but electrical resistance/flow remains constant as output resistance increases....correct?

Don't know if it's a mag drive or not, they didn't say. I would suspect not if it's a piston or rotary diaphragm style, why?

The term "Mag Drive" refers to a non contact coupling method, usually in pumps between the impeller and motor, allowing a sealed pump chamber exclusive of mounting the impeller directly to the motor shaft as close coupled pumps. In short, the pump is totally isolated from the motor and you don't have to worry about conventional seal failure which could smoke a motor or contaminate the fluid.

As far as duty cycle, it has nothing to do with a magnetic coupling. That will either be a motor issue or a compressor issue.

Sounds like I'm waaaay over my head as far as pump details go. But that's why I'm hob-knobbing with you guys!

Sounds like everyone is going with AC pumps, and looks like many setups without batteries; planned on aerating during daytime only anyways, which would be well suited for planned solar setup

Will therefore spring for the relatively cheap inverter and go with the vibe I am getting from the PBF - and get a $200 5 CFM AC pump with readily available rebuild kit.

Thanks for all the input!

JKB, I know the style "mag-drive" you mean. The style I refer to is similar to many aquarium filter pumps used. A permanent magnet on a shaft held in place with a bushing/bearing on one end or both ends with an electromagnet is pulsed, driving the shaft magnet.

I believe Rainman you are correct. 99% of DC diaphragm pumps are just a giant electro magnet / relay design.

I have been running a diaphragm pump for three years now with no rebuild. This said pump... pumps air to two single vertex disks one at 14 feet the other at 12 feet. The key to this is I have a small soaker hose air station at 4 feet that is just cracked open to allow the pump to start during start up. If the pressure starts to build faster then the pump starts it will stall the pump and burn her up.

First two years I run it 24/7 but this year I found we were over aerating the pond so we run it 12 hours now. In the winter once we have ice forming then back to 24/7. There was air bubbles forming on the rocks and plants all around the pond. I took this as a sign of over aerating.

Cheers Don.

P.S. it is very important to look at the sellers other items they are selling. I expect it would be very difficult to get a rebuilt kit for this above pump.