In searching to get my "ducks" in order for aeration . I have been seeing these used Gast pumps from "hospital use" Other than rebuilding the vane section if the pump motor runs they should function OK. Electric motors can have a long life.
$200>300 sounds like good deals. The difference between vacuum and compression is just which port you use is that correct ?
Any comments pro or con
http://www.ebay.com/bhp/gast-1023

1023 may be overkill for my 1/4 acre wet spot - see link

In a small pond that requires only 1-3 diffusers look for the smaller horsepower Gast compressors model 0523 (1/4-1/4hp). Make sure they are oilless. The lower hp will run cheaper and produce ample air for most all ponds less than 1 acre compared to a 3/4hp. The 3/4hp 1023s produce twice as much air volume(cfm) as the 0523. With a rotary vane do not try to push air any deeper than 18ft or you are overworking the system, motor and vanes. For depths of 17-20 ft mount the diffuser on a stand so it releases bubbles at 16-18ft depth and the rotary will work fine.

Fin,

I have a Gast 0523 1/3 hp in my 1 acre pond and it does GREAT!! You just got the best answer above you could get from Mr. Bill so I will say no more except that I do have a oil less vane pump I run mine at about 9 feet and it's sweet!

RC

OK thanks for the info and I know what to look for now.
Great forum - I am learning as fast as I can remember which is not very long. LOL

The other question was it doesn't matter if it says vacuum or compressor ? They the same ?
My thinking is it just depends on which port you hook to. ?

The inlet port is the vacuum part and the outlet or pressure opening is air psi producing part. The pumps do both - vacuum and pressure depending on your purpose for the pump. Oiless is the important feature.

OK Bill thanks- that was my hunch but needed pro verification before putting any green out.
Now to get with my electrical friend and see whats needed for a 300' run to a picnic /tractor shed area.. Ouch !

Fin don't forget you can run PVC 300 feet no problem instead of your electric. It will take a few extra seconds for the air to run through the pvc but it will still do the same job. That may be a cheaper route for you to take versus running 300 foot of electric line.

Unless you want the pump down by the ponds edge. I know a lot of guys out here run their pumps several hundred feet away from the pond and use PVC pipe to make the long run. Just FYI.

RC

RC
Thanks for the comeback but Dear wife wants electricity at the picnic cookout area.
The middle of which will have garden/tool/pond storage area 8x16. The plans are for the pole type shed barn 16x48 under roof - it will be sectionalized - open 16x16 for cookout -closed in 8x16 storage and 16x24 open equipment storage.
I will pipe pvc from the Pole structure/compressor another 100 feet to pond and the weighted line into pond.
We already have house water at a hydrant 1/2 there so plan on extending that at same time.
I raise chickens back there so the water and electricity will be a plus
thats the plan.
Thanks, Tom

What do you plan on plugging in at the end of this run? Be realistic.

Gast 0523 , 10 lights [60>100 watts], battery charger if needed, two 500 watt heat lamps and two 150 watt deicers - electric fence charger - maybe small electric pump to pump pond water to garden.
Thats all I can think of but I am sure the Princess will add something else LOL
We are thinking running 224 alum service wire off a 100 amp breaker in barn to a 100 amp service panel at shed . leaves a little room for something if needed later.

224 alum will be too small for 100 amps. Good for 20 amps @300' tho.

JK
I was going with what the electrician said but in checking I got the tape wheel out and its
closer to 260' . Most likely going to need 1/0,1/0,1/0 which doesn't seem to be much more $.
If that doesn't make it I can always lower the barn breaker amps some. thanks
for the info.

Straight 120V @ 100 amps @ 260' will require #500MCM (kcmil) alum cable.

If you drop a 10Kva 240x120 transformer at the end, run 240V from the main breaker to the barn, run the 224 alum, after the transformer go the circuit breaker panel, you'll have 80 amps @ 120Vac for use.

1/0 alum will support a 15Kva transformer for 125 amps for that run.

You can probably get a 10Kva transformer for about $500.00, if you shop around. I always use Dongan shielded transformers. They are a bit more, but the output is quite clean. I always have expensive electronics on the other end and that's the reason for the shielded transformers. It's a minimal cost to help protect expensive devices.

OK we have settled on the Gast 0523 [ or AT05] for aeration.

Do to the increasing costs of the electric run we are on hold on that to accumulate green.
We are going to do it but may be next spring.

However I have fry fish stocked and need to get air flowing.
!. Will that Gast push air in 3/4 or 1/2 " black tubing 420' then another 50' in
weighted line ?
2. What diffuser do I need - suggested name brand and model for this 1/4 acres.
Info on pond at bottom link.
3. The gast needs a intake filter but the rest of the line can be direct is that correct ?

Thanks, Tom
"

Absolutely it can push air that far! I supplied 6 membrane discs at 18' deep, plus 2 at 10' deep from 800' away using 1/2" poly supply line. Pressure never topped 10psi.

1" poly is still cheap and will cause way less friction loss over 1/2 or 3/4".

I'm curious as to why a transformer is needed at all? Standard 220/240V is nothing more than 2, 110/120 power leads. Run it as 220. install a circuit box and ground rod, good to go.

Where is your neutral to bring it to 120V? This is split phase. L1, L2, Neutral and ground.

The problem Rex, is that you need much larger conductors for lower voltages in long runs. It is more economical to run the higher voltages from L1 and L2 (240V) of your split phase service, drop a transformer at the end and that will provide you with the neutral to drop down to 120V.

Exactly my point....L1=110/120V, L2=110/120V Common neutral, common ground. L1+L2=220/240V, again, using common ground and neutral...or is this being installed in Europe?

I completely understand using higher voltage to reduce amperage, and thus wire size, but a $500 transformer will cost more than larger wire for the distance. What I am failing to see, is where the power supply is ever at 240V when standard home drops in North America are 2, 110/120 feeds. I see no gain at all in combining the L1and L2 at the barn, adding a transformer, and getting back what you started with, minus distance/transformation losses.

It's about running large and expensive cable for long distances to get the 120V at the amperage you want without a huge voltage drop at the end of the line. If your voltage drop is too much, your amperage will increase. Still the same watts, but you can over amp things and cause potentially deadly issues.

It's less expensive to pop a transformer in at the end of a long run with the higher voltages. Ground at the point, transformer provides the neutral for 120V. If not, you need to run the larger cables due to potential.

Transformer goes at the end of the run.

You wire it the way you want to, and what works for you.

If it is a new pond I would not be overly worried about getting it done this year. New ponds very rarely have fish kills. A new pond should be able to go two years without aeration and still be in good shape. Although early aeration is beneficial. Fish kills occur primarily in ponds with some age and accumulated bottom deposits.

I definitely get it and am very proficient in the simple equation of amps X ohms = Volts. I just completely disagree that a 260-300 foot run supplying 100 amps is very large, or expensive....certainly less than a transformer and adding new components to fail. I like the KISS theory, and this is a pretty simple feed for the amps needed and relatively short distance. The run only needs to handle 50 amps per feeder line for 100A total. Completely agreed the feeder line should have at LEAST a 10% higher amperage capacity than the anticipated need.

In this case, #500 aluminum direct bury, run 300 feet drawing 60 amps per 110V leg will have .039 ohms and a max voltage drop of 2.167V at full amp usage. Very usable and tolerable for all but the most delicate of electronic equipment.

Using #400, for about $.20 more per foot would double capacity and reduce voltage drop. Still considerably cheaper than a transformer and wire. Plus, a very safe, straight forward, uncomplicated installation

What are you transforming at the end of the run??? 120V back to 120V??? Something is missing here....That is why I originally asked why a transformer is needed? He is starting and ending with 2, 120V feeder lines...

Going from 240 to 120 with a neutral and ground.

It's alternating current either between one leg and a neutral which is 120V, or between the 2 legs that are 240V. 240 needs no neutral, but 120 does. You run the 240 out with much smaller wire (2ga) and bring your 120V neutral from the transformer.

It really is not common for residential services to extend beyond the household, so transformers are quite rare. But, with a lot of people wanting to do long runs, it's usually best to go with the higher voltage run and cut it down at the end, where you will be using it. It was less expensive going this route and the power output of the transformer is quite clean, better than line service.

Whatever you want to do is fine with me.

OK guys - I know very little about juice runs but I will say two country electricians have told me we can do it with #400 or 500 . But I am checking with a friend that is an electrical engineer.
JKB - I appreciate your input it made me recheck and triple check what to do and we still haven't decided.
Rainman - love your truck driver - does he require bonus milkbones like mine?

Bill thanks for the information - that takes some of the pressure off.

One more question - someone is selling ring diffusers are they ok or should we go membrane type. 1/4 acres so what is the best / least aggravating

Some one tell me what to look for.
Thanks , Tom

I would go with the Vertex diffusers. Talk to esshup.

Okay, now I understand. JKB's method simply combines the 2 120Vac leads at the home service drop, drops the need for the neutral wire, adds a transformer to restore your output to what you had originally at the home service drop. I asked because in all my years, I have never seen it done that way, yet in reality, on "long" runs, I suppose it is done that way by the Utility supplier, when adding another service drop from a transformer off the 1200Vac service main lines.

Thanks for finally explaining the how and why of your design, JKB. I understand it completely, yet still believe on THIS run, I'd think a transformer is much more costly than the additional wire, overall. Plus, a user quality transformer is prone to failures much more often than those used by utilities. As far as I can see, the transformer will save a minor voltage loss (assuming there is not already an equal loss on the 240V feeder line), probably cost more, and loses a few total available amps over direct feed.

FinnFur, here is the story of my driver...our now deceased Pondboss Mascot.....

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=193065&page=1

Whichever way works best for the situation. A transformer is just another option.

What a teary eyed story - sorry to hear deceased but his last years seemed like his best ones with a family.
Reminds me of Chocolate lab Spike - he was my favorite/RIP
We have 4 rescue dogs now - love em all but you always have favorites just like children.