EIT 5150 CHLORINE MONITOR POST ADDITION DISSOLVED CL2 (mg/l Powers on. $199 The screen displays 0.38. I cannot get the numbers to change.. I have no idea how this works. Please buy as is.. FYI........ From the internet... The monochromator 24 or 26 error message indicates that not enough light is getting to the detector. 24: monochromator indicates a lower light condition than 26: monochromator. Replace the lamp if it has not been replaced recently; lamps can loose intensity over time without burning out. If the lamp was just replaced, check to see if the wires from the lamp are in the light path or touching the mirror. If so, tuck the wires out of the way of the light beam and away from the lamp. If the visible lamp was replaced, check to be sure the base of the lamp bracket is fully in the recessed area; if not completely in the recessed area the lamp will be mounted at a slight angle. If the lamp has been replaced and is installed correctly but you still get the error message, the instrument will need to be serviced. All items listed are identified as either new or used and the new may be older surplus. We list all items to the best of our ability and aim to provide the customer with as much information as possible. Yaba1957 is not liable for any products sold, the customer is responsible for proper testing, installation and use of equipment purchased. No warranties are expressed or implied.The sale of this item may be subject to regulation by the U.S. Food and Drug Administration and state and local regulatory agencies. If so, do not bid on this item unless you are an authorized purchaser. If the item is subject to FDA regulation, I will verify your status as an authorized purchaser of this item before shipping of the item. Domestic Shipping . We ship using UPS and FedEx to provide en-route package tracking. International Shipping We ship using UPS, FedEx and USPS. Items shipped by UPS and FedEx are more efficient and provide customers with en-route tracking. Items shipped by USPS cannot be tracked . International buyers are responsible for any and all applicable customs, duties, taxes and fees. ****KEEP IN MIND ALL OUR PRODUCTS HAVE NON REMOVABLE TAMPER PROOF HOLOGRAMS AND WE KEEP SERIAL NUMBERS AND DIGITAL PHOTOS OF THE PRODUCT ON FILE! WARANTIES AND RETURNS WILL BE 100% VOID IF THEY ARE REMOVED OR REPLACED WITH NO EXEPTIONS!****