I too have a pre-2019 configuration Geo 612; two of them actually. Both were bought very early in 2019 before the new 612 version was released (or I just got old stock from an online retailer). I measured the sound increase using a decibel app on my phone and it was an unbearable increase of 7-8 decibels.
I actually just
posted this a few hours ago before on how I fixed the problem for my setup last week before I saw this thread and response. Do at your own risk as I'm sure this will void your warranty and probably won't be supported by Geo after the modification.
From:
https://www.reef2reef.com/threads/r...he-rest-of-the-coral-farm.569126/post-7530320
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A little DIY action post today. I’ve been sick of the noise that I’ve had from my Geo 612 calcium reactor (Pre-2019 version) for a long while now, but finally got around to doing something about it. My Geo reactors would always end up collecting air/co2 gas which made a crazy amount of noise once the Sicce pump recirculated it. I measured it with my phone and the reactor added 7-8 decibels to ambient noise level. I’ve tried everything that didn’t include physical modifications to the actual reactor. Changed from pulling to pushing tank water, took apart the whole reactor and used liquid Teflon tape and silicon grease everywhere; no matter what I did, air always ended up driving up the noise of the reactor.
Here’s a picture of the pre-2019 unmodified unit (pic from google)
The problem was that air didn’t get much of a chance to get released from the reactor before it was recirculated in the pump. Although the outlet was in the top of the manifold, the outlet was exiting horizontally and in the middle of the manifold. The newer models (sometime in mid-2019) changed the input and output to be at the top of the lid.
2019 Model with input/output on lid
So what I did with the lid was lower the input of the recirculating inlet so the air could collect above that inlet and added an output of the effluent above that point in the lid so the air would definitely exit before recirculating.
To lower the input of the recirculating pump, I used a flexible extension tube that came with the Innovative Marine spin stream return nozzle. It was almost perfect to fit snuggly, but nothing Teflon tape couldn’t fix. I used this solely because I had it sitting around. I’ve seen some 3D printed ones, but this works just fine.
I then used a tap drill bit to add a 1/4” NPT threaded hole to fit a 1/4” John Guest push connect elbow. I used RectorSeal Pipe Thread Sealant to ensure elbow didn’t leak.
You can see the inlet in the middle is lower than the John Guest elbow (the small hole), the effluent output, so air should now exit the main reactor to the secondary reactor chamber without any air being sucked into the recirculating pump.
One of the 1/4” push connects on the manifold now needed to be plugged up and John Guest makes these great stem plugs that give a nice clean look. You can see a whole plug sitting on top of the lid.
And here’s another shot of the new elbow in the lid.
So far so good. Quiet as can be and visually looking at it, the reactor doesn’t look like it’s collecting any air at all. No leaks so far either. Hoping this is a solid fix.
Part List
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1/4” NPT tap (I actually used a 1/2" step drill bit to drill the 7/16" hole and not the 7/16" drill bit included with this tap to make the initial hole before using the tap. I find it much easier to use and less likely to crack the acrylic versus switching out standard drill bits from smaller to bigger).
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1/4” NPT thread John Guest Elbow
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1/4” John Guest plug
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RectorSeal Pipe Thread Sealant