CO2 controller not engaging due to stable PH - The Planted Tank Forum
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post #1 of 3 (permalink) Old 08-15-2017, 04:03 PM Thread Starter
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CO2 controller not engaging due to stable PH

This question I am sure has been asked before but I have not been able to locate a direct answer either on this forum or on other resources as well.

First some details:

Tank/filter - 125 gallon tank with sump with two filter socks and a refugium with java moss and java fern.
Lighting - 2 x 18" Satellite Plus Pro freshwater and 1 x 48" Satellite Plus Pro freshwater
In the Tank -
  • Eco Complete substrate to approximately 3"
  • 3 Large pieces of Malaysian driftwood
  • 80 or so tetras of different species, 2 GBR, 3 Angelfish, 1 Roseline shark, 6 corys, snails and shrimp for cleanup crew
  • 2 large sword plants and 3 dwarf swords, 1 crypt, 1 java fern mat. 3 bunches microswords, 1 water sprite, 1 dwarf lily, 6 bunches val, 4-5 anubias, and 3 anachris like plant that I can't recall the name.
Water Parameters
PH - hovers around 7.02 - 7.04 lately
KH - 3
GH -7
TDS - 220
Temp - 82.5

PH System
I have a 10# cylinder hooked to a CarbonDoser regulator controlled by a American Marine Pinpoint PH controller that feeds to an reactor before returning to the tank. Set with a high point of 7.2 and low of 6.8 as per the recommendations in the user manual.

I do 20% water changes weekly with a 70/30 RO to Tap ratio to maintain the same parameters as tank.

Now to my quandary. When I first installed the CO2 system it would engage about 1 hour after lights on as the PH exceeded the high point and would remain on for 4-5 hours before reaching the low point and shutting off. It would not engage at night and the PH would remain in range until lights on. For the past week and 1/2 the controller has not engaged and the PH has remained extremely stable day and night. Plant growth is not exceptional but everything looks healthy and nothing is melting. Should I be concerned that I am not injecting any CO2 at this point or will the plant s eventually use enough during photo period to start engaging the controller again? Should I lower the high and low settings to get the controller engaged? I have minimal algae growth that is so far controlled by the snails and amano shrimp with little cleanup required by me.
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post #2 of 3 (permalink) Old 08-17-2017, 11:57 AM
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Probably reset your low point would be the solution, I know most guys shoot for one full pH level drop with most high tech CO2 injection systems by lights-on. I'm only regurgitating information though, I don't have a high tech setup. Someone with more experience should probably comment.
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post #3 of 3 (permalink) Old 08-17-2017, 01:06 PM
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Recommended pH is nonsense really. Your only aim should be to get your pH down by 0,8-1,0. Turn the CO2 off, let the tank water degas for a few hours (preferably 24h), measure pH, set high point to measured pH minus 0,8 and low point at -1,0. With 1,0 pH drop I'm getting to 6,0 in my tank, no worries at all :-)

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