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