pH Control
pH is hard to control in a hyposalinity solution because at this dilution, the buffer ability of the diluted saltwater is not good. Be prepared for this.
Make pH adjustments with pure baking soda (e.g., Arm & Hammer) you find in the grocery store, or better yet is sodium carbonate. Sodium carbonate can be made in the home oven. Take a pound of pure baking soda and spread it out evenly on a large cookie sheet. Put into a preheated oven to 350F. Bake it for 30 minutes. Take the sheet out of the oven, let cool to warm and put into an air-tight, clean container for use. Now the baking soda has been turned into sodium carbonate, a more potent pH + additive.