Sharon's ph problems

To: Aquatic-Plants at actwin_com
Subject: Sharon's ph problems
From: Pat Bowerman <bowerman at rog_ar.ispnet.com>
Date: Sat, 25 May 1996 22:57:20 -0700
References: <199605251939.PAA07917 at looney_actwin.com>
Sharon wrote
(snip)
 My
> controller, needle valve and solenoid are all Sandpoint and they seem to work
> fine. Controller turns the co2 on when the ph hits 7.3 and the co2 comes out at
> a steady 1 bubble per second.
>   Substrate is Estes Aquarium Gravel "Bit o' Walnut"  ( I love the names these
> people come up with <g>)
>    And yes, shamefully, the ph has been playing havic with my tank. I've lost 6
> ottos, one by one.  First hair algae took over, then I was plagued with
> blue/green.  The blue green is now gone, and the hair algae dissapeared the week
> I had the ph under control--but the hair algae is back.  1 bubble/second seems
> like a lot of co2 to me, but do you think I just need to turn it up?  I'm afraid
> of gasing the fish.

Sharon,
    I believe that earlier you wrote that your KH was about 3. According to George 
Booth's FAQ, you can safely drop your ph to about 6.8 with no problems. CO2 levels below 
30ppm should definitely be safe for your fish. At a ph of 8.0 and a KH of 3, your CO2 
level would be about 0.9 ppm or almost nil! 
    Why it would be that low if your reactor is installed properly and is operating 
properly is beyond me. My guess is that something is definitely wrong with your reactor 
setup. The CO2 should enter from the bottom of the reactor via a long tube that connects 
to the tubing at the top of the reactor. This is where you should be seeing the bubbles 
entering the reactor. From here, the bubbles work their way to the top (sometimes 
gradually, sometimes not) of the reactor where they are trapped and violently swirled in 
the water flow. The bubbles should stay trapped here until they are dissolved into the 
water. If they are being blown out the bottom of the reactor by the water flow, then you 
have too strong a water flow entering the reactor, and you need to open the green bypass 
valve below the point where your water flows into your reactor. If, indeed you are 
blowing your CO2 out the bottom, then your reactor is not being allowed to function 
properly and is virtually worthless to you. You are simply bubbling the CO2 into your 
water where 95% of it is escaping into the atmosphere.
    Also, did you say that your controller was set at 7.3? Again, according to the 
table, with a KH of 3, you would need the ph to be about 6.8 to have an optimum amount 
of CO2 for your plants.
    Although there might be a danger of gassing your fish, there is far more danger in 
having an erratic ph. One last thing, a KH of 3 is fairly low. This means that you have 
a pretty low buffering capacity in your water. You are then more vulnerable to wild ph 
swings than someone with a KH of 8 or so. What are the chemical properties of your tap 
water. 
    Good luck with both the fish tank and the baby!
                                                            Pat