How to replace diaphram for a Airtech 80

[farne230]

My BD is run by a Airtech AT80 aerator. It ran continuous for three years, no problems. I ordered a replacement diaphragm kit (about $65 + shipping) and within three days I was ready to install.

At first my koi did not know what to do, they detected the aerator was off IMO because of noise and reduced DO. The koi would huddle together lifeless, on the third day they began to move around more. Before I installed the Airtech, the DO dropped to 5.1 at about 77f to 80f. Ten min. after I started it up again, DO rose to 6.1...Wow.

I thought I would share a few photo's about replacing a diaphragm on this pump, it may help someone in the future.

When you receive the replacement kit it will contain two diaphragms (comes in two pieces) and two washers and nuts. Place a towel on a hard flat surface and preferably in a air-conditioned room near a plug so you can test the unit before you reassemble it.

(ref to the phot's attached in the order they were taken)

Step 1: Take the top off the unit by unscrewing the large knob, remove the cover and this will expose a gasket and thin filter sponge, set this aside. Clean the sponge in water and air dry.

Step 2: Turn the pump upside down, unscrew the four screws along the perimeter. The cover should now be loose, if not tap the sides or use a flat screw driver to pry the edges. I had to tap the air discharge softly to loosen the cover. This will expose the two diaphragms and magnet.

Step 3: Remove the white plastic protective sleeve sets around the whole unit and set aside. This will expose the two diaphragms. You will only work on one at a time.

Step 4: Unclip the hose and remove hose from diaphragm cover. Unscrew the four screw holding the diaphragm cover in place (you will reuse these screws and washers). Now you will see the diaphragm. Inspect the diaphragm if torn replace.

Step 5: Replace the diaphragm by un-bolting the nut on the center of the diaphragm. Take it all the way off and set aside. In your kit you have a new washer and nut. The diaphragm may stick, firmly pull and it will come off and discard. Replace with a new diaphragm, the copper slotted center faces the magnet and you push into place, also one side has a notch which fits into place. Take your new nut and washer and tighten into place, and place a little pressure to set the diaphragm. Attach the new diaphragm cover, first attach to hose and clamp, then align cover so all four holes match and firmly press against diaphragm, it will snap into place. Add the four screws and washers and tighten.

Step 6: repeat step 5 & 6 to replace second diaphragm.

Step 7: plug unit in and make sure it works (it will be loud). If it does not work then the problem may be something else. If it works continue to step 8.

Step 8: Replace the white plastic shield around the diaphragms. Blow off any loose powder or dirt. Place the Cover back on, so the slot covers the plug outlet correctly. Turn upside down and replace and tighten the four screws that hold the cover. Set the unit right side up and replace the sponge filter, gasket and cover then screw Nobe down. You are ready to reinstall into your pond.

[RookieKoiGuy]

I dunno why these diaphram kits are double the price of all
the other brands......I have had mine replaced 3 times

[farne230]

I agree, the price is a bit high in my opinion. That is why since I replace both diaphrams, only one was torn, I will keep the old spare for future use. I assume typically just one diaphram fails at a time.
Bob

[woodyaht]

In the first pic.............. Do ya think your hammer/single jack was big enough?

Sorry someone had to say it

[MCA]

As I remember, someone wrote an article in KOIUSA last year about how to do maintenance on linear diaphragm air pumps.

I gave up on Airtech, Alita, Hakko...etc. Parts are way too expensive. You can get a brand new Dolphin AV150 delivered with a spare set of diaphrams for ~$150. The spare diaphragms were ~$20 as I remember.

When the Airtech 120s on the Nexuses die....they will be replaced by Dolphins.

[farne230]

The hammer was for support and thanks for the good advise on the Dolphin brand air pumps, I will look into these for that price.
Bob

[MCA]

removed....

[jnorth]

Interestingly enough I have two older Airtech 40s and what I thought was an Airtech 80 but it turns out it was a newer Top Ponds 80. Had to replace the 80s diaphram already but the Airtechs are 4 years in with no problems. I love my Airtechs.

[RookieKoiGuy]

Most of the air pumps are very much the same inside
EA just gets more for the rebuild parts...
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RookieKoiGuy Ogata Showa Grow-out form

[moikoi]

i have a Medo running the bio for 2.5 yrs now with no problem.the Dolphins pump are excellent value. you can buy an extra one for back up.