Well, this is an old thread, but it was referenced elsewhere (think twice before buying from CTC). From that reference it was clear that the problems described in this thread were still relevant.
In general consumer use there are two completely different products that are used to adapt voltage (240V or 220V to/from 120V or 110V) and/or frequency (50Hz to/from 60Hz) for use of appliances in countries where the appliance was not originally intended to be used. The commonly used names are "converters" and "transformers". Unfortunately, the marketing people that write the advertising copy that is used on product packages, and catalogs, often interchange the names, and/or improperly describe the item. Thus, because most places that sell them either don’t understand the difference, or completely ignore the issues involved, it is difficult for a consumer to get information as to how to differentiate, or even to know that there is a need to differentiate between a "converter" and a "transformer".
As an example of marketing people interchanging the types, the site www.220-electronics.com claims that "converter" and "transformer" are interchangeable. They should know better than that. This site was one of the first hits I found, and their prices do not appear too out of bounds. They have a section that appears to be exclusively transformers , but also sell some converters (1 , 2 , 3 ).
"Converter": These are usually cheaper, lighter, and more common than transformers. They are active electronic devices that convert either just the voltage, or both the voltage and frequency of the input to the output. They, unless explicitly stated, output square waves (some may output "modified sine waves" without stating that they do, but don’t count on it). They are often not suitable for use with devices that use an AC motor (e.g. a pump). Using this type of device with appliances that have AC motors (e.g. a pump) may work, but can also cause all of the types of problems described in this thread (overheating, non-function, etc.). A cheap example of this type of device can be found at Outpost.com with a 1600W model running $16.99 (the 1600W may be a peak rating; the description provided is insufficient to tell). Depending on the kind of equipment, these can also have problems with electronic equipment. There are significantly more expensive models that have additional functionality. It appears that the cheaper converters only adapt voltage, and do not perform frequency conversion.
Somewhat more expensive Converters will output what is usually stated as a "modified sine wave". Such converters come much closer to providing the sine wave output that is needed for most AC motors. If reasonably designed, these have a acceptable probability to function with more devices. They will also have fewer problems with electronic equipment. Even more recently, converter products have been introduced that output "true sine waves". These tend to be more expensive.
Converters are often advertised based on their peak output power instead of their continuous power output capability.
Transformer: These are usually heavier, and often more expensive. Transformers are basic electronic devices that are, essentially, just some wires wrapped around a metal core. They output sine waves. They do not convert frequency. However, they are almost always functional with appliances with AC motors.
Probably the easiest way to tell the difference between a "Converter" and a Transformer is weight. A "Converter" is usually light ("1600W" is <= 1 lb). A Transformer will be dense and heavy (200W >= 3 lb).
Many/most AC motors do not require the frequency of the input voltage to be converted in order to be functional. However, if the frequency of the input power is not converted, then the motor will run at a different speed than that for which it was designed. This will probably not cause a problem in this situation (I don’t have a XL-3000, so I can not verify this).
For use with the CTC pump you will want to get a Transformer.
Earlier in this thread it was stated that the power specification for the XL-3000 is 100W. Personally, I prefer at least a bit of headroom in specifications, so I would get at least a 200W transformer. Such can be ordered from www.220-electronics.com for as little as $9.99. Should you desire extra functionality, they have 5 different types with additional features and power ratings up to 15,000W. They do ship internationally, but do not quote international shipping rates (other than Canada) directly on their web site.
I am sure there are many places that sell such transformers. I have no attachment to the use of 220 Electronics - International Relocation TVs DVDs Converters & More. I found them merely as a result of a Google search. I have not done any business with them. Thus, I can not provide any feedback as to the quality of their service.
[NOTE: Many simplifying assumptions have been made here. Details I considered not relevant to this situation have been left out. I have also ignored various possibilities that are not as common, and probably do not affect this specific situation.]
makyen