Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Segment Reporting Information [Line Items]
Sales	$ 147,801	$ 140,043	$ 290,973	$ 287,379
Gross Profit	32,797	27,994	63,773	56,791
Selling, General and Administrative Expense	16,221	14,817	31,259	29,653
Operating income	16,576	13,177	32,514	27,138
Industrial [Member]
Segment Reporting Information [Line Items]
Sales	61,171	68,090	132,673	143,415
Gross Profit	10,436	10,674	22,893	21,589
Selling, General and Administrative Expense	6,429	5,895	12,496	11,991
Operating income	4,007	4,779	10,397	9,598
Water Treatment [Member]
Segment Reporting Information [Line Items]
Sales	49,540	45,868	89,254	89,120
Gross Profit	14,522	12,753	25,861	24,844
Selling, General and Administrative Expense	5,573	5,134	10,866	10,122
Operating income	8,949	7,619	14,995	14,722
Health and Nutrition [Member]
Segment Reporting Information [Line Items]
Sales	37,090	26,085	69,046	54,844
Gross Profit	7,839	4,567	15,019	10,358
Selling, General and Administrative Expense	4,219	3,788	7,897	7,540
Operating income	$ 3,620	$ 779	$ 7,122	$ 2,818