pH Drop - Should I Be Worried?

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Twoapennything

Aquarium Advice Freak
Joined
Jan 18, 2010
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410
Location
Denver, Colorado
I live in Colorado where high pH is the norm. My 40 gallon tank's pH level has slowly been dropping. It had been 7.8 since I got the tank and set it up. Over the past week it's dropped to 7.4. Yesterday the pH was 7.4; today it was 6.6. Should I be concerned about this? If so, what should I do? Thanks in advance for any replies. Oh, and I haven't changed anything - food, chemicals, etc. are all the same as usual.
 
Well,
In a saltwater tank, your fish would all already be dead at 6.6. So obviously you have a freshwater tank. Freshwater tanks usually hover around 7, a neutral ph. Anything lower than 7 is acidic. Purchase a chemical to raise the PH a bit and buy test strips to monitor the PH for a few days.
 
do a water change at least 50% dont buy any chemicals to raise ph if you have to you can use baking soda stay away from test stips thay are not as good as the api drop test are better
 
Agreed , do a water change and avoid the chemicals . How often do you make water changes ? My water is a 7.8 from the tap and will drop over a period of time , I have found a 50% water change once a week (every Sunday) keeps it steady . Once you start messing with chemicals , the Ph will yo-yo up and down , and this adds stress to the fish .

I also agree with ampa one on the test strips , they are inaccurate , use the test kits that use reagents .
 
Yikes, please disregard mmaglione's advice. Both are bad and can be costly mistakes. What is your water change frequency and amount? Frequent water changes prevent pH fluctuations by constantly cycling the dissolved solids out of the tank that contribute to this phenomenon. I would recommend 25% once a week as a starting point. Tap water if you are on well can change if a large amount of precipitation has occurred (public can as well to a lesser extent). But it's unlikely this is the cause.
 
You need to understand buffers, GH & KH before you can understand & manage pH swings.
So read this first:
Beginner FAQ: Water Chemistry

Without understanding buffers, adding ANY pH altering chemicals will lead to disaster! I agree with all the warnings above.

How often are you doing pwc's?
Your dropping pH may be one of 2 things:
1. You don't do enough pwc's & are using up your buffers. Solution - do more pwc's!
2. Your source water has varying pH. this is not unusual in areas that get water from limestone aquifers. The water is usually high in KH & pH, except during spring melt or heavy rain when the rain/snow dilutes the water & drops everything. <It is pretty warm out west this year, are you guys into the spring melt already?> In that case, you should monitor the pH/KH of your source water & consider adding a buffer source (eg crushed coral.)

At any rate, I would suggest you check your KH in the tank vs your tap to see what is going on.
 
Just following up on the pH issue - I read the water chemistry FAQ very carefully and decided to try and raise the buffer, or KH, by adding 3/4 of a teaspoon of sodium bicarbonate (baking soda). I dissolved the baking soda in a small amount of tank water and added it. Today, the pH is 7.6. I will be monitoring it carefully, and not just with the High pH chemicals. I think what happened is that my high pH tests were coming out at 7.4 - the lowest reading on high pH - and the pH was actually dropping much lower than that. So, I'll be using the regular pH test first, and the high pH test if the regular test is at the highest reading.

Today's tank readings were Ammonia 0.0, Nitrites 0.0, Nitrates 0.0, and pH 7.6. I'm tentatively hopeful that I've managed to cycle my 40 gallon tank! The 10 gallon tank cycled easily, but the 40 gallon has given me some problems. I figured out a good system for PWCs that makes them quick and easy, so I've been vigilant about keeping the water fresh. Yay for successful cycling! :)
 
Sounds good. Just remember there is no replacement for water changes, they are the #1 best thing you can do for your fish/plants. Good quality water limits/prevents disease, reduces stress on the fish, and helps to prevent bad algae and bacterial outbreaks that can occur when a nutrient is depleted.

Twoapennything, when I started trying to grow plants in my tank I also messed around with the baking soda thing since my GH was only 2 degrees (~25-30ppm if I remember my conversion?). I added baking soda at each water change and did this for nearly a year. Then one day I just decided it wasn't really needed (my main reason for using it was CO2 injection dropping the pH pretty drastically), and haven't looked back since. I would caution you if you are going to use it to make a stock solution and dose in a liquid manner as opposed to adding it dry to a cup of water. There is just too much variability in a 3/4 teaspoon scoop IMO. You can just make up a 5 or 10X solution and then add an ounce or so (find out how much you're adding and match it to what you are currently doing). You'll be much more consistent doing it this way.

But honestly, I'd just forget about the baking soda and keep up on the water changes.
 
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