My little pH project

pH Meters and things

Hi Guys OK this is going to be a long one so hang in there --- :bigsmile:

Firstly the good news - I have just purchased a lab grade pH probe and amplifier - the price : R770-00 for the probe and R550-00 for the amp.. For a lab grade setup this is VERY cheap and I will happily pass on details on where to get them ex Jhb.

The reason I bought it is for the "Famous Fish Room" which will be a thread by Veegal (My Georgeous wife) starting tommorrow.

What I propose to do is fairly simple. Take a 100 litre drum of water, next to that take a 20 litre drum. Put the pH probe in the 20 litre drum and add about 18 litres de-chlorinated water. Stir gently. Add acid slowly ( using a piece of air pipe and an electrically controlled valve ) and let the pH instrument control the acid dosing valve. This way I can set the pH required and control it to 2 decimal points or better. When the pH is at the required value (can be set anywhere) pump the water into the 200 litre drum and repeat until there is 200 litres of the correct pH water. This is then circulated to all the tanks, and new pH correct water is made up when needed.

I recently completed a project at work for a pharmaceutical lab that was growing "Bugs" to make vaccines. In that project I had to keep the water at 37 degrees +_ 0.2 degrees, pH at 7.15 +_ 0.05, Dissolved oxygen at 98% ( This varied quite a bit as the bugs grew and used up the O2 ) and we kept a watch on Optical density (How clear the water is) to monitor how well the bugs were growing.

So keeping a constant pH is relatively easy if you have half a million rand to throw at it. The trick is to do it at home for as little as possible. What I am trying to do is get correct pH water at the least possible cost. So far I am in for the cost of the pH probe and amplifier. Add the cost of the tanks and the control valve and I am hoping to get away with about R2000-00 all in.
I have access to a controller so that cost I am saving..

If anyone wants details of this system and how to go about it give me a shout Ill be happy to pass on what I know.