Bill when you do this, make sure to rinse out every last bit of the ref solution vials.

Use the KH diluted solution with a pippette and rinse the vials and make sure the rinse water goes into the KH diluted solution.

So you pour the 10ml vial into the 3.488 liters of DI water(total= 3.498).
Mix, then take a 10-20ml amount of the this 3.498 4 KH water anmd rinse out any leftovers in the vial and return that rinse water to the 4 KH solution.

This gets every last bit of the 10ml ref solution into the 3.488 liters of DI water.

If you lose say 0.25 mls, that's a lot since the ref solution is so concentrated and such a small volume, so make sure to get every bit, or submersed the vial into the 3.488 liters of DI water and rinse that way(Na2CO3 is not toxic or hazardous etc).


Regards,
Tom Barr