Note 10 - Segments and Geographic Information (Details) - Additional Business Unit Gross Profitability Detail for Products Segment (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Products segment net sales:
Products segment net sales	$ 5,988	$ 7,904	$ 18,702	$ 20,878
Products segment gross profit:
Products segment gross profit	1,414	1,959	4,637	4,448
Pool and Commercial Products [Member]
Products segment net sales:
Products segment net sales	2,612	4,159	8,503	11,354
Products segment cost of sales:
Products segment cost of sales	1,668	2,892	5,490	8,077
Products segment gross profit:
Products segment gross profit	944	1,267	3,013	3,277
Government Products/ Research and Development Services [Member]
Products segment net sales:
Products segment net sales	1,272	1,679	4,305	3,713
Products segment cost of sales:
Products segment cost of sales	1,018	1,381	3,389	3,441
Products segment gross profit:
Products segment gross profit	254	298	916	272
Products Segment [Member]
Products segment net sales:
Products segment net sales	3,884	5,838	12,808	15,067
Products segment cost of sales:
Products segment cost of sales	2,686	4,273	8,879	11,518
Products segment gross profit:
Products segment gross profit	$ 1,198	$ 1,565	$ 3,929	$ 3,549