Segment Information (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Jan. 01, 2017	Oct. 02, 2016	Jul. 03, 2016	Apr. 01, 2018	Apr. 02, 2017	Apr. 03, 2016
Summary of Segment Information
Sales		$ 126,990	$ 118,053	$ 125,395	$ 133,731	$ 118,618	$ 112,351	$ 121,250	$ 131,374	$ 504,169	$ 483,593	$ 413,976
Gross profit		17,806	18,840	24,115	25,999	21,913	20,912	27,032	28,216	86,760	98,073	80,257
Selling, general, and administrative expenses		14,670	14,139	14,828	15,766	14,468	14,916	14,871	15,126	59,403	59,381	49,086
Goodwill impairment		39,116	0	0	0					39,116	0	0
Operating (loss) income		(35,980)	$ 4,701	$ 9,287	$ 10,233	7,445	$ 5,996	$ 12,161	$ 13,090	(11,759)	38,692	31,171
Identifiable assets	[1]	376,688				404,524				376,688	404,524	403,967
Capital Expenditures										19,703	21,616	24,183
Industrial [Member]
Summary of Segment Information
Sales										247,374	238,555	251,749
Gross profit										29,619	38,886	37,967
Selling, general, and administrative expenses										21,159	21,818	22,137
Goodwill impairment										0
Operating (loss) income										8,460	17,068	15,830
Identifiable assets	[1]	165,052				159,032				165,052	159,032	158,015
Capital Expenditures										10,265	10,529	17,712
Water Treatment [Member]
Summary of Segment Information
Sales										138,465	128,954	128,312
Gross profit										36,268	35,962	35,470
Selling, general, and administrative expenses										19,426	19,798	19,261
Goodwill impairment										0
Operating (loss) income										16,842	16,164	16,209
Identifiable assets	[1]	58,513				53,445				58,513	53,445	50,013
Capital Expenditures										7,228	7,777	6,306
Health and Nutrition [Member]
Summary of Segment Information
Sales										118,330	116,084	33,915
Gross profit										20,873	23,225	6,820
Selling, general, and administrative expenses										18,818	17,765	7,688
Goodwill impairment										39,116
Operating (loss) income										(37,061)	5,460	(868)
Identifiable assets	[1]	153,123				192,047				153,123	192,047	195,939
Capital Expenditures										2,210	3,310	165
Unallocated Amount to Segment [Member]
Summary of Segment Information
Identifiable assets		$ 14,300				$ 13,100				$ 14,300	$ 13,100	$ 32,800

[1] Unallocated assets, consisting primarily of cash and cash equivalents, investments and prepaid expenses, were $14.3 million at April 1, 2018, $13.1 million at April 2, 2017 and $32.8 million at April 3, 2016.