Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Apr. 03, 2016	Dec. 27, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 28, 2014	Sep. 28, 2014	Jun. 29, 2014	Apr. 03, 2016	Mar. 29, 2015	Mar. 30, 2014
Summary of Segment Information
Sales		$ 129,513	$ 88,375	$ 94,592	$ 101,496	$ 93,281	$ 83,825	$ 88,881	$ 98,036	$ 413,976	$ 364,023	$ 348,263
Gross profit		25,002	14,709	19,811	20,735	15,531	13,642	18,122	18,496	80,257	65,791	61,600
Selling, general, and administrative expenses		16,067	12,825	10,303	9,891	9,532	8,697	8,271	8,875	49,086	35,375	33,510
Operating income (loss)		8,935	$ 1,884	$ 9,508	$ 10,844	5,999	$ 4,945	$ 9,851	$ 9,621	31,171	30,416	28,090
Identifiable assets	[1]	403,967				194,017				403,967	194,017	170,507
Unallocated Amount to Segment [Member]
Summary of Segment Information
Identifiable assets		32,800				53,700				32,800	53,700	66,700
Industrial [Member]
Summary of Segment Information
Sales										251,749	249,066	244,888
Gross profit										37,967	33,619	32,041
Selling, general, and administrative expenses										22,137	19,793	19,781
Operating income (loss)										15,830	13,826	12,260
Identifiable assets	[1]	158,015				151,157				158,015	151,157	141,506
Water Treatment [Member]
Summary of Segment Information
Sales										128,312	114,957	103,375
Gross profit										35,470	32,172	29,559
Selling, general, and administrative expenses										19,261	15,582	13,729
Operating income (loss)										16,209	16,590	15,830
Identifiable assets	[1]	50,013				42,860				50,013	42,860	29,001
Health and Nutrition [Member]
Summary of Segment Information
Sales										33,915	0	0
Gross profit										6,820	0	0
Selling, general, and administrative expenses										7,688	0	0
Operating income (loss)										(868)	0	0
Identifiable assets	[1]	$ 195,939				$ 0				$ 195,939	$ 0	$ 0

[1] Unallocated assets, consisting primarily of cash and cash equivalents, investments and prepaid expenses, were $32.8 million at April 3, 2016, $53.7 million at March 29, 2015 and $66.7 million at March 30, 2014.