Milwaukee MA 957 Regulator

[Scottiemac]

Is anyone using the MA 957? I like it a lot. loaded the chamber with VG and can see the bubbles quite well.

Here's the problem, though. I can't seem to dial in my bubbles. The control is very tight and it's hard to tell if I've moved it at all, so I move it a bit more noticeably and suddenly it's like giving my reactor a bubble-bath. Finding that sweet spot is very touch and it's as though it doesn't drop the reactor into melting range at all, or it does it in just ten minutes.

Does anyone else have this problem? If so, what did you do to correct it?

 

[cdemoss01]

Problem Breakdown​

• CO₂ bubble control is too coarse. Tiny adjustments don’t register, and slightly larger ones flood the chamber.
• Reactor swings between no dissolution and excessively low pH, rapidly dissolving media.
• Very narrow margin for adjustment, making it hard to stay in the sweet spot (~6.5–6.7 pH depending on media and goal).

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Solutions​

1. Upgrade to a Fine Needle Valve​

Your current valve may be the issue. Look for:

• Swagelok or Ideal Valve (like Model 52 or 55) – These are precision needle valves and allow micro-adjustments to bubble count.
• Apt-Aquatics Pro CO₂ Regulator (or similar) – Many reefers report excellent control with these because they use lab-grade needle valves.

This is by far the best bang-for-buck improvement.

2. Use a Secondary Bubble Counter​

Adding a secondary bubble counter closer to the reactor (vs. only at the regulator) can make bubble count easier to observe and respond to. Many fine needle valves come with these integrated.

3. Switch to a Peristaltic Feed Pump (if not already)​

If you're using tank pressure or a gravity feed to push water through the reactor, switching to a feed pump like a Kamoer FX-STP2 or Versa gives you tight flow rate control, which stabilizes how CO₂ behaves in the chamber.


This won’t directly affect CO₂ tuning, but helps stabilize internal pH.

4. Use a pH Controller (Optional but Helpful)​

A controller (like Apex with pH probe in the reactor) can shut off the CO₂ solenoid at a set point. This helps prevent media melt-down if you overshoot.


Set CO₂ to turn off at pH ~6.4–6.5 and back on at 6.7. It won’t fix your bubble control, but it’s great insurance.

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Quick Fixes While You Upgrade​

• Set your regulator to very low pressure (~5 PSI or less). Lowering the delivery pressure gives you finer bubble control.
• Always wait 10+ minutes after adjusting the needle valve to see the full pH response in the reactor.
• If your needle valve sticks or feels “springy,” it’s likely bottoming out or isn’t meant for CO₂.

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Summary: Fixing the Touchy CO₂ Control​

Problem	Best Fix
Coarse control	Upgrade to a lab-grade needle valve
Overreaction to tweaks	Lower delivery pressure (≤5 PSI)
Wild swings in reactor pH	Add pH controller fail-safe
Bubbles hard to monitor	Add secondary bubble counter