When you say colorimeter you mean spectrophotometers like the Hanna for PO4. Colorimeters are also things like color wheels and those Seatest/Fastest kits also. Nope Don there are none. The issue is really with things like Ca++, Mg++ and Alk which are titration. And Alk is a different beast. They will do Ca++ and Mg++ but the levels are only to a few ppm. At the levels we deal with there is waaayy to much interference with Ca++ for Mg++ and Mg++ for Ca++.
How nice it would be if Loivbond or HACH had a kit where all you need to is change the color disk for their colorimetric comparators for x parameters. On another note HACH does make a so called complete seawater kit but it is better to build your own by selection through HACH. This is what I did, Randy has it all now. But such a kit is pricey, mine was on the order of $500. It all came in its own custom case from HACH but the PO4 is separate. Almost all kits are titration par pH, NO2, NO3 and NH3, which are similar to std As Seatest/Fastest/IO kits.
My kit was the following
Alkalinity, Acidity, Salinity, Chloride, Total Hardness, Ca++, Mg++, O2, CO2(for FW not SW) and I threw in the AS Fastest changeable plate kits for NH3, NO2, NO3, Copper and pH. Silica, Iron and Tannis /Lignin were also separate kits like PO4
