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Ric,
The Astronomik Ha (type II) filters have an IR blocking coating/film. There is no need to couple a separate IR blocking filter to the Ha filter. In fact, doing so is likely to slightly reduce the quantity of light reaching the chip. I wouldn't be concerned about UV as the filter has such a narrowband pass centered around the 656.3nm. UV is down the other end of the spectrum , around the ~310nm mark which the filter is already blocking.
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