Bettas like slightly acidic water but my tap water is basic with a pH at 7.8. Should I add pH down? How fast should I let the pH fall?
A: This is a great question. PH can be confusing and even when you know the numbers knowing what to do with them can send an aquarists head spinning. I will try and keep it as simple as possible. PH is the Power of Hydrogen and measures how acidic or basic your water is. Readings below 7.0 are acidic, readings above 7.0 are basic and 7.0 on the dot is called neutral. This logarithmic scale is used to measure everything from battery acid to lye.
Most aquarium fish live in water with a pH range between 6.5 and 8.0. Individual species thrive best in water with a pH close to their natural environment. This can prove to be challenging if your fish is adapted to the acidic water of a Malaysian rice paddy but the water pumped into your house is basic. Commonly, an aquarists first response is to panic and dump in drops of pH-Up or pH-Down to “fix” the problem. If this describes you then the first thing I need to say is “STOP, and put down the bottle. Now slowly step away.”
Yeah, ok, I’m being a little dramatic but I have good reason. Here’s why you should think twice before adjusting your waters pH.
First, that logarithmic scale I was talking about earlier… Well that means the units are being measured ten-fold. That denotes a pH of 6.0 is 10x more acidic then a pH of 7.0 and a pH of 5.0 is 100x more acidic then a pH of 7.0. Sure, the numbers seem so small (5, 6, 7) but their impact can be serious. A rapid fluctuation, especially toward acidic can cause what aquarists call a “pH crash”. This is when the pH drops quickly and everything that once was living is now compost in the bottom of your tank. Within a matter of a few minutes, every fish in your aquarium can die from a rapid and sever pH fluctuation. If severe enough it can even kill off all your beneficial nitrifying bacteria.
The second thing to consider is your carbonate hardness, also called buffering capacity (KH). Simply put, water with a high KH level is well buffered making it difficult to change the pH. You’ll have to add a lot more drops of that pH-Down in well buffered water then in water with a low KH level. Very low KH levels can mean the pH may fluctuate on it’s own and in some cases pH crashes occur naturally. Many major cities treat their water so the KH is very low allowing the facilities to alter the pH levels before pumping the water out to the masses. It’s a great idea to test your tap water’s KH so you have an idea of your buffering capacity. If your KH is very low or high you may struggle with keeping your pH stable. As mentioned earlier, unstable pH is much more dangerous then one that isn’t ideal but stable.
The third thing to know is that most fish, including bettas, can adapt to your water’s pH levels. Bettas can do very well and live long healthy lives in a pH of 7.8. The important thing to understand is that in basic water, toxins like ammonia and nitrite become exponentially more dangerous. Since your pH is high you will need to be very diligent about your cleaning regimen and I strongly suggest anyone with basic water cycle a tank for their betta rather then using a betta bowl where 100% of the water is changed regularly.
So before you reach for that pH adjuster bottle, think twice and consider if your betta will be better off without it.