Exhibit 10.29


                                            April 28, 2000

Mr. John H. Schroeder
20 Byron Drive
Mt. Laurel, NJ  08054

Dear John,

      Supplementing the terms of your Employment Agreement with Sybron Chemicals
Inc.  (the  "Company"),  this will confirm  that,  in the event there shall be a
Change in Control (as  hereinafter  defined) and thereafter your employment with
the Company  terminates  Without Cause (as  hereinafter  defined),  you shall be
entitled to the following benefits:

      (a)If your  employment  terminates  prior to the first  anniversary of the
date of the  Change  in  Control,  you shall be  entitled,  in lieu of any other
severance pay (except as provided below), to a lump sum payment,  payable within
30  days  of the  date  your  employment  terminates,  equal  to the  sum of the
following:

         (i)      two times your base salary in effect on the Change in Control
date; and

         (ii) your Target  Bonus (as defined in the  Company's  Executive  Bonus
Plan (the "Plan")) for the year in which your termination  occurs,  prorated for
the number of months of service during that year prior to the termination; and

         (iii) your full Target  Bonus for each of the two years  following  the
year in which your termination occurs.

      (b)If your employment  terminates on or after the first anniversary of the
date of the  Change  in  Control,  you shall be  entitled,  in lieu of any other
severance  pay, to a lump sum payment,  payable  within 30 days of the date your
employment terminates, equal to the sum of the following:

         (i)      one time your base salary in effect on the Change in Control
date; and

         (ii) your Target Bonus for the year in which your  termination  occurs,
prorated  for the  number of months of  service  during  that year  prior to the
termination; and

         (iii) your full Target Bonus for the year  following  the year in which
your termination occurs.

      The value of each Target Bonus  payable  hereunder  shall be determined in
accordance with the provisions of Section  7(g)(4) of the Plan, as amended.  The
number of shares of

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Company  Common Stock awarded for partial years shall be determined by prorating
the Closing  Price (as  defined in the Plan)  based on the Closing  Price of the
Common  Stock  on  December  31  immediately  preceding,   and  on  December  31
immediately  following,  a date  which  is two  years  prior  to the  date  your
employment terminates.

      Notwithstanding  anything  herein  to  the  contrary,  in  the  event  the
aggregate  present  value,  determined in a manner  consistent  with  applicable
provisions of Section 280G of the Internal Revenue Code of 1986, as amended (the
"Code") and Treasury  Regulations  promulgated pursuant thereto, of the benefits
and/or  payments  provided  to you under the terms  hereof  that are  treated as
Parachute  Payments (as hereinafter  defined),  along with the aggregate present
value  (determined  in the same manner) of all other  payments  and/or  benefits
provided  to you by the Company  that are also  treated as  Parachute  Payments,
exceeds  three times your Base Amount (as  hereinafter  defined),  the  benefits
and/or payments to which you are otherwise entitled under the terms hereof shall
be reduced to the extent  necessary so that the  aggregate  present value of all
Parachute  Payments to which you are entitled  hereunder and any other agreement
or  arrangement  with the Company shall not exceed three times your Base Amount.
The reductions  required under this paragraph,  if any, shall be applied, to the
extent  possible,  to all payments  and/or  benefits to which you are  otherwise
entitled  under  this  Agreement  in  proportion  to the  Present  Value of such
payments  and/or  benefits,  and  otherwise in such manner as the Company  deems
appropriate  at its  discretion.  In the event you  receive  Parachute  Payments
having an aggregate present value in excess of three times your Base Amount, you
agree that you are not  entitled  to retain and shall  immediately  repay to the
Company,  in cash,  the excess of the  aggregate  present  value of all payments
and/or benefits which constitute  Parachute  Payments over three times your Base
Amount.  For  purposes  of this  paragraph  the  following  terms shall have the
meanings set forth below:

      "Parachute Payment" means any payment to you in the nature of compensation
that  constitutes a "parachute  payment" as that term is defined in Code Section
280G(b)(2); and

      "Base  Amount"  means the  amount  which is  determined  to be your  "base
amount" as that term is defined in Code Section 280G(b)(3).

      Termination of your  employment  with the Company Without Cause shall mean
(a)  termination  by the Company  without  Cause (as defined in your  Employment
Agreement  with the  Company),  or (b)  termination  by you by reason of (i) the
Company's  failure to make any of the  payments,  or provide any of the material
benefits (or their  equivalent),  under the terms of your  Employment  Agreement
with the Company,  or (ii) any material  adverse  change in your  position,  the
location   of  your   primary   workplace,   the  scope  of  your   duties   and
responsibilities, or your compensation and benefits.

      A "Change of Control"  shall be deemed to have  occurred upon the earliest
to occur of the following events:  (a) the sale or disposal of substantially all
of the  assets  of the  Company,  or (b) the date any  entity,  person or group,
within the meaning of Section

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13(d)(3) or Section 14(d)(2) of the Securities Exchange Act of 1934, as amended,
other than the Company or Citigroup or any of their  subsidiaries,  any employee
benefit plan (or related trust) sponsored or maintained by the Company or any of
its subsidiaries,  or any other person or group in which the present  management
of the Company  shall have an  aggregate  equity  interest,  on a fully  diluted
basis, of no less than 15%, shall have become the beneficial  owner of, or shall
have  obtained  voting  control  over,  more  than  fifty  percent  (50%) of the
outstanding  shares of (i) the Company's  Common Stock, or (ii) the Common Stock
of the Company resulting from the merger or consolidation of the Company with or
into any other entity.

      In the event of a sale by the Company of its Ion  Exchange  Business,  you
may  elect,  by  written  notice  to  the  Company  within  30  days  after  the
consummation  of such sale,  to  receive  the  benefits  set forth in the letter
agreement  dated July 5, 1995  between  the Company and you, in which event this
letter agreement shall be of no further force and affect.

      If the above correctly reflects our  understanding,  please so indicate by
signing in the space provided below for such purpose.

                                           Sincerely,



                                           Richard M. Klein
                                           President and Chief Executive Officer

AGREED:

/s/ John H. Schroeder
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John H. Schroeder