Cannot get ph down with Reactor

daviesri

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I built the Rex Grigg reactor in order to better disolve the CO2 in my tank. Out water here comes out of the tap with a pH around 7.8. I have been running about 2 bubbles a second and it is not going below 7.1. I had been told that for a 72 gallon that 2 bubbles per second should be enough. I have bumped it ip to 3 and it still stayed above 7.0. All I have for filtration is an Eheim 2217 and nothing else for water movement. The reactor is on the outlet side of the filter. Any ideas?
 

VaughnH

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I think you need more than 2 bubbles per second for that size tank. I used much more than that on a 29 gallon tank, and I use more on a 45 gallon tank. May I suggest that you try the "drop checker" method for measuring how much CO2 you have in the water, then you can jack up the bubble rate without worrying that you are overdosing CO2?
 

Sintei

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daviesri;11498 said:
I built the Rex Grigg reactor in order to better disolve the CO2 in my tank. Out water here comes out of the tap with a pH around 7.8. I have been running about 2 bubbles a second and it is not going below 7.1. I had been told that for a 72 gallon that 2 bubbles per second should be enough. I have bumped it ip to 3 and it still stayed above 7.0. All I have for filtration is an Eheim 2217 and nothing else for water movement. The reactor is on the outlet side of the filter. Any ideas?
Firstly, as VaughnH said, bump up the CO2. 2-3Bubbles/second isnt just cutting it.
Secondly, why do you want the pH below 7.0? Everyone is obsessed with pH nowadays. Generally fish and plants doesnt care (unless its very low/high). Instead, bump it up a notch everyday and watch your fish at the end of the day. When they start to surface and gasping for air, turn down the CO2 a notch and voila, youre set.
 

daviesri

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Heck, I was under the impression that the plants did care. I know the fish don't. At the current pH of 7.0 and KH of 9 degrees I have a CO2 level of 27 ppm. I guess all is OK then and I will not worry about bumping up the CO2 to reduce the KH and pH.
 

Tom Barr

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They do not care about pH, they do care about CO2 if one generalized and drew comparisons.

I can have a pH of 7.2 and a CO2 of 35 ppm and KH of 20.

Likewise I can have a KH of 1 and pH of 6.0 and a CO2 of 30ppm.
Plants generally will do better in the higher KH waters under high light.
Some plants, maybe 5-10 species will do better in the softer water, but it's less likely to be due to pH, and much more due to KH.

We can artifically change the pH with various organic acids easily, and leave the
KH the same. The same effect is noted for several species under this situation.
So KH is more likely the issue and the cause rather than pH.

KH is only part of the issue(CO2 is the other part), assuming pH drives everything is a poor assumption as well.


Regards,
Tom Barr