API pH UP Freshwater Aquarium pH Adjuster 473 mL (16 fl oz)

Make sure to read the instructions very very well and dose slowly. My ph went from 6.2 to 7.6 within a month. I no longer have lethargic shrimps and the snails and plants are doing great.

works great raising my aquarium ph water in my area has very low ph put a little in my tank each weak to keep my ph stable

This works really well and quickly, it just doesn't last very long which is why I knocked a star off. I have a tank with a large piece of driftwood that tends to drop the pH and in addition to crushed coral, I occasionally have to use the pH UP to keep the levels balanced. It does a good job but only lasts a day before I have to do it again.
It works well in emergencies or when I don't have time to change the water that day but need the levels balanced quickly to avoid harm to my fish until the next day when I can do a proper change, but for long-term use this is not the way to go. I would still recommend this to have (as well as pH DOWN) for emergency use, but bouncing the pH drastically is going to do more harm to your fish than letting them adjust to slightly higher or slightly lower levels.