I recently aquired a Linde/Union Carbide HDA-300 mounted on a water cooling cart of approximately 24gallon capacity (Bernard?) with a gear driven pump mounted on the rear. The machine is in excellent condition and welds great on Aluminum with my current air cooled TIG torch. I am looking to connect a WP-20 in the near future and am trying to sort out the water cooling system. There is a glass filter looking device on the rear of the cart just before the water return line enters the storage tank. My problem is that this glass cylinder is empty (No Filter). Is there supposed to be one in there, and if so, does anybody know where I can get a replacement? Also, the Linde owners manual recommends adding methanol to the distilled water for low temperature operation on high frequency. Has anyone tried methanol? The flammability issue scares me, but the price for the Miller Low Conductivity coolant is very expensive at 24 gallons. Any suggestions are appreciated.