Barr Aquatic Systems

Probe Holder Box and Flow Meter Kit Instructions:


Inspect all items closely upon receipt. Any damage must be reported to the shipper with 24 hours, or they may not cover the damage. Contact us immediately if there looks to be damage. We will repair or replace the part(s) as needed. Unfortunately we can take no action until the damage claim is validated by the shipper.

Things to look for:

  • Check the box for damage before opening. Take pictures if it looks obviously holed or crushed.
  • Check for cracks in the acrylic, especially at joints.
  • Check that all parts are accounted for (nothing fell out of the box).
  • Compare the invoice included in the box to insure that all items expected were received.

Installation Sequence:

  • Assemble the flow meter kit (if needed) by inserting the flow meter in to the acrylic holder, and pushing on the two Ell fittings from the back. Make sure that the screw holes in the bracket are DOWN for mounting the flow meter on a PHB or a Calcium reactor base.
  • Mount the flow meter with the included black nylon screws, in an orientation that will allow you to view it.
  • Fill the PHB 3/4 full with media- Carbon, Phosguard or more CA reactor media is fine. Keep the smaller chamber near the exit fitting free of any media to prevent the output fitting from clogging. Rinse gently with RO/DI water to wash out any unwanted media dust.
  • Insert the two long back thumbscrew though the lid and in to the PHB. Pick a spacer that matches the thickness of your sump rim- 1/4, 3/8 or 1/2" are all provided as short tubes or rods. Place the rod in the groove under the clamp, and slide the unit over the lip of the sump. Tighten down the thumb screws. Note where the water exits the PHB (fitting in end) and make sure that is where you want your effluent to drop in to your sump. A short tube may be added to the fitting if desired.
  • Connect the output of the reactor to the flow meter bottom, and run a short tube from the top fitting on the flow meter to the fitting on top of the PHB.
  • Install the lid on the PHB and you are ready to go.
  • You should never need to use pliers on the thumb-screws, just snug them up by hand.


Check the flow meter daily for proper flow though your reactor. For a "normal set point" pH probe (turns the CO2 OFF when the pH drops below the set point), drop the pH probe in to the second chamber though the hole in the top and let it settle for 30 seconds, then read the pH. Then return the probe to the sump.

Note that the reading as taken in the PHB should be the same as the second chamber of the reactor, and normally .2 to .3 higher than the first chamber.


The unit should be removed and cleaned when you change media, to cut down on algae growth. Use a scrub brush (no soap) or similar to clean it out.