I have a 155g tank that I'm getting ready to re-plant. I'm going to be
adding a CO2 system to it and am considering a PH controller. I was
wondering if anyone had any advice as to:

1) Whether this is really necessary
2) Which one is better

Thanks,
Blake

If you decide not to get a controller, I would recommend getting a permanent
visual CO2 monitor. I just ordered one from Dupla. My pressurized CO2 in
my 55 gal has worked well. The only problem have been when I changed things
and didn't realize the co2 implications. Such as switching from a hang on
the back filter with biowheel to a canister. I almost killed a tank full of
fish when the pH got to 6.0. So, since I am basically lazy and rarely test
my water unless there is an issue, I hope the co2 monitor will keep me out
of future trouble.

Bob
"Blake" wrote in message
...
I have a 155g tank that I'm getting ready to re-plant. I'm going to be
adding a CO2 system to it and am considering a PH controller. I was
wondering if anyone had any advice as to:

1) Whether this is really necessary
2) Which one is better

Thanks,
Blake

"Blake" wrote in message ...
I have a 155g tank that I'm getting ready to re-plant. I'm going to be
adding a CO2 system to it and am considering a PH controller. I was
wondering if anyone had any advice as to:

1) Whether this is really necessary
2) Which one is better

Thanks,
Blake

Don't need it and will not help.
Get a pH monitor instead, this is cheaper and has the accurate display
of pH etc.
You adjust the pH by setting the needle valve which will hold a steady
pH in a weel designed system as good as most any pH controller set
ups.

Regards,
Tom Barr

I have a controller also, I did this in my pressurized system for a couple
of reasons. I killed all my fish the first time I sprung a leak the tank
pressure went low then dumped the last few hundred psi of Co2 into my tank.
Then there was the time I did not know the tank was getting low and the high
pressure system dumped all the CO2 into my system and killed the fish again.
I know I am a novice I have only been keeping fish for five years now but
the piece of mind from my controller is great. Not to mention I can see the
PH without doing any testing. The hobby is supposed to be fun.
"Bruce Geist" wrote in message
...
Just one point. The PH controller will typically also read out the PH of
the water on a continuous basis. A controller is probably 100 to 120 US
dollars more than a simple PH monitor. In addition, for a controller
based
system you would need a solenoid on your valve unit which is an
additional
expense.

In total, for a controller based system, you are looking at another 150
bucks or so extra cost-- assuming you are going to buy a PH monitor as
suggested by Bob and Tom if you don't get a controller. I s'pose that
will
buy a lot of plants! (I am happy with my set up though..)

As I said in my previous post, get the details on successful,
non-controller
based systems and try to replicate that. The reactor will affect
performance greatly, as will your valve's fine adjustment capabilities.
Tom's configuration suggestion is no doubt a good one. -Bruce Geist

" wrote in message
om...
"Blake" wrote in message
...
I have a 155g tank that I'm getting ready to re-plant. I'm going to be
adding a CO2 system to it and am considering a PH controller. I was
wondering if anyone had any advice as to:

1) Whether this is really necessary
2) Which one is better

Thanks,
Blake

Don't need it and will not help.
Get a pH monitor instead, this is cheaper and has the accurate display
of pH etc.
You adjust the pH by setting the needle valve which will hold a steady
pH in a weel designed system as good as most any pH controller set
ups.

Regards,
Tom Barr

I guess I haven't figured out how the controller makes anything safer. If
the probe goes out of calibration it could cause the controller to call for
more CO2.

The cure for CO2 end-of-tank dumps is a needle valve working against a
pressure head.

There seems to be a difference of opinion about the value of removing CO2
input during the night but it is easy to do either by cutting of the flow or
reducing the effectiveness of the diffuser during the night.

Simple sounds best to me.

jtm

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On Tue, 11 Feb 2003 10:30:53 -0800, Dave Millman
wrote:

However, about 3 weeks ago my dual gage regulator-needle valve system ran out of
gas. It did an end of tank dump. pH dropped from about 6.4 to a bit under 6
before I noticed fish behavior and turned it off.

So a needle valve does not prevent an empty tank pressure dump.


Yes it does.
You had some other funky thing happening in this system, eg the check
valve etc.
I've run my tanks down over the years many times.
I've watched the pH carefully with a pH monitor.
I never got any variation till the tank was compleley out and then the
pH went up.

I use clippard needle valves and have done this same experiment at
least 6 times on my own system and have heard the same thing from at
least a dozen others.

I have a German check valve on the hose from the regulator to the reactor.
The whole system came from M3 about 15 months ago.

Not sure what they sold you.

I've seen cases where the regulator pressure was set VERY low (2psi)
and the resulting increase when the "tank dump" happened caused in a
CO2 overdose. But if the regulator pressure is set higher, the
needle-valve needs to be closer tighter, and when the output pressure
rises, the needle-valve still limits the CO2 and prevents problems.

Ditto here.

Additionally, if there is a check-valve located after the
needle-valve, the needle-valve often has to be set at a higher rate in
order to overcome the resistance of the check-valve. Some
check-valves cause problems, others don't.

Ditto.
I don't use check valves, nahnannahnah! But I don't need them the way
I design my CO2 system.

This is really interesting. In between my last post and this, I was up at a fish
store that told me about a fish die-off they attributed to not turning off the CO2 at
night. I looked at their tank: needle valve, no cover, lights suspended 8 inches
above the tank, no chance of CO2 being trapped above the water and displacing O2.

That would not occur anyway.

I don't like check valves. Unless you are adding the CO2 under
pressure in line etc, there's no call for them. By feeding the CO2
into a suction side of a pump, only positive suction pressure is
applied. No negative backpressure will ever occur even if the tank
runs out of gas, it's only neutral 0 pressure then.

No check valve to stick or get clogged and blow out at the last second
etc.

Like I said, I've watch carefully the effects of a tank going all the
way down to zero pressure many times. I've never had anything remotely
like a dump in any way.

I can therefore attest to the neelde valve's ability without any check
valve, solenoids, diffusers etc to muddle anything and my measurement
were accurate using a well calibrated pH monitor.

Regards,
Tom Barr