| I have been running a Stoelting Aquaeous machine and has been performing very well however. the maintanance dept cleaned using the descaler and now we are seeing boards with a removable thin film. We are going to to drain all the water and change all the carbon beds will this be a good start. I am open to suggestions. | After using any descaler in any machine, it is ESSENTIAL to thoroughly wash out the machine 2 or 3 times, then rinse with DI water a couple of times. The machine must be run for several minutes during all these phases. I don't know the Stoelting machine, but most machines keep a residual 0.5-1 l of water in the pump(s) and pipework, so you will have this amount of dirty descaler solution before the first wash, which will just be a simple dilution. After several washes/rinses, the quantity of residual descaler will become small (but always finite). Any closed-circuit filters (carbon, DI, RO, mechanical) should be short-circuited during descaling, washing and first rinsing but should be put back into circuit for the last rinse.
There are many formulations for descalers but they are all acid, ranging from hydrochloric (not recommended for stainless steel machines) through to short-chain (usually < 4 Cs) mono- and di-basic carboxylic acids, blended with powerful ionic surfactants (hygroscopic when dried). If the residues from these are not carefully eliminated from the machine, you will be in Severe Trouble.
If you descaled with the filters in circuit, you should change/regenerate them as they will, in all probability, be saturated.
Hope this helps