pH up

[Courtney Edwards]

I finally put the effort into finding sources for pH up that aren't from the hydroponics store, and it turns out I can get both, easily, in my small town.

calcium hydroxide is known in the masonry world as hydrated lime or masons lime. It's cheap (8$CDN for 25kg) and you can get it at any home building supply store. 

potassium hydroxide is sometimes also known as lye, however, take note that lye can also be sodium hydroxide so double check the ingredient when you buy it. It is used in soap making, brewing, making biodiesel, and apparently plumbers use it to clean pipe fittings. It can also be bought at a higher price at soap making supply stores and at most home supply stores in the plumbing section (8$CDN for a water-bottle size).

Remember that these are caustic alkalies and can burn your skin and eyes so use caution and appropriate protective gear. And store them both in airtight containers to keep them from absorbing moisture from the air and turning into weird piles of goo. 

[Vlad Jovanovic]

If you do decide to go the route of making your own KOH out of the ashes of hardwood trees and distilled water (or rain water, melted snow whatever) do yourself a BIG favor and DON'T do it in an aluminum container (or even a galvanized one) hehe...

It's super easy to do, and is a great way to use ashes which you might otherwise have just throw away...(if you heat with wood).

[Jon Parr]

In a pinch, you can make KOH by dripping distilled water through wood ashes. Baking soda (sodium bicarbonate) will also work quickly as both a pH up, and a source of carbonate. It should not be used regularly, die to sodium buildup, but it's fine for emergency, especially if your KH is dangerously low. And of course, soaking bags of limestone, marble, seashells, oyster grit, or coral will release a slow but steady supply of CaCO3 to buffer up an feed the bacteria. Whether you use should use a hydroxide or carbonate should be decided on your KH, or carbonate hardness. I like to keep mine around 100, but 40-300 is okay. Below 40 and you risk a bacterial crash. I know, it happened to me.