PH fluctuation questions

[catfishacr]

Got some PH Questions.

- Is it normal for Prime to lower the PH temporally? Prime lowers my PH 0.5-0.8 for about 12-18 hours then returns to normal.

- Is it normal for tank water PH to fluctuated thought the day and night? My PH fluctuates between 7.45 and 7.8 daily.

My tap water chemistry

- PH comes out at 9 and after 24 hours it settles around 7.8-8.0

- KH is hard to pinpoint but is between 53.7-71.6

- GH I’m not 100% sure but it is hard water. I can test if that would be useful.


I have a PH probe in my tank 24/7 to measure the PH and I use API liquid test kit for all other testing.


Is all this normal?

 

[Woefulrelic]

Your kh is low. As waste is produced it will push kh lower. The ph swings are most likely caused by this. Baking soda will raise your kh without impacting gh.

 

[duanes]

I just googled Iowa Cities water quality report, the link is below.
If you scroll down the link, you will find most of the info you need about your tap water.
Unless you are on your own private well.
Day/night pH changes are very normal, especially if you have any higher plants and/or algae growth in your aquarium, because during the day the plants use CO2 and give off oxygen, at night the plants give off CO2.
But pH can also change depending on your water change routine, if your tap water is low in buffers, more frequent water changes may be needed to maintain a stabile pH.
The way your pH changed after just doing a water change, suggests there are enough metabolism byproducts (acidification) present that a more rigorous water change routine may be needed to control these by-products. Some people think water changes are only about nitrates, but I disagree. Water changes are also about maintaining stability, and if pH constantly and immediately drops, more volume, and more frequency may be needed.
http://www.amwater.com/ccr/quadcities.pdf

 

[catfishacr]

I just googled Iowa Cities water quality report, the link is below.
If you scroll down the link, you will find most of the info you need about your tap water.
Unless you are on your own private well.
Day/night pH changes are very normal, especially if you have any higher plants and/or algae growth in your aquarium, because during the day the plants use CO2 and give off oxygen, at night the plants give off CO2.
But pH can also change depending on your water change routine, if your tap water is low in buffers, more frequent water changes may be needed to maintain a stabile pH.
The way your pH changed after just doing a water change, suggests there are enough metabolism byproducts (acidification) present that a more rigorous water change routine may be needed to control these by-products. Some people think water changes are only about nitrates, but I disagree. Water changes are also about maintaining stability, and if pH constantly and immediately drops, more volume, and more frequency may be needed.
http://www.amwater.com/ccr/quadcities.pdf

Yeah im on Iowa city tap. I do have large pothos and philodendron plants roots in the water and the ph is lower at night. So that makes a lot sense!

For the water changes I do 20% a week. I fill up two brute trashcans (60 gal) and let the ph gas out from 9 to 8, then i pump it to the tank. So tank is only primed for 60 gallons in a 300 gallon tank. Such little prime lowers the ph.

I hear you on the acidification im not the best at keeping the canister filters super clean. That might be contributing.

I want to do larger water changes pumping the water straight from tap to tank and no trashcans. Im worried though it might mess with the ph to much with tap water 9ph and tank water 7.45-7.8 ph. Throw in that prime lowers the ph .5 dosing 60 gallons who knows how much it might drop dosing 300 gallons.

Also the ph doesn't lower in between water changes it just fluctuates from day and night.

Any suggestions on the water changes? Thanks for the help man!

 

[Pomatomus]

That's a really high pH to be coming out of the tap. Especially considering the alkalinity. The pH swings day/night make sense as others have mentioned, but I'm having trouble figuring out the tap water pH of 9.

I would normally expect the pH of the tap water to rise with time as CO2 gasses off. I haven't really heard of it lowering. Does your city use chlorine or chloramines? Maybe this can happen when chlorine gasses off? Anybody know?

 

[duanes]

If you check out the link of the OPs city tap water, when it leaves the plant, the tap water pH averages 7.8.(highest recorded in 2015 was 8.1)
I'm wondering if the OPs probe is not being calibrated enough, if the salt block (if the probe has one) has worn out, etc etc.
In the lab, we would calibrate pH probes daily in order to get accurate results.
And I would say a 20% water change once per week, may be the reason there is a large tank water pH shift.
In order to maintain a stable pH I changed 30% every other day.
Sometimes 30% every day, especially in summer when the older tank water could be use on the garden or lawn.
A 20% water change is hardly enough to replace the buffers eaten up by metabolism.
The Pothos will help with nitrate, and thus reduce acidification slightly, but does nothing to add buffer, and because it is a terrestrial plant, does not add CO2 to the water, only aquatic plants do that.

 

[catfishacr]

Hey the link you provided duanes was for Quad city not Iowa City. The Iowa City water report doesn't included ph. Ive called them and they have told me the ph is 9.25. The probe is only 6 months old and calibrate it once a month. The tap water i get reads 9.0 with the probe and when i test with the api test kit i get a dark purple and the test kit only goes to 8.8, the api kit shows its at least 8.8. so im pretty sure its accurate that my tap ph is 9. Ive tested the water after it sits for 24 hours with both the probe and the api kit and get the same thing ph of 7.8-8.0.

I agree i need to do larger more frequent wc's. But still dont know if its safe to have my fish go through such a fluctuation every time i do a wc. I also tested last night putting 30 gallons of water into a trashcan and primed it right away. the prime lowers the tap water as well, so its not just the prime lowering the fish tank water.

Thanks for the help guys, im open to any suggestions
Let me know if you need more info or want me to try anything!

 

[duanes]

If you do more frequent water changes, your pH probably won't fluctuate so much.
By adding water that buffers pH more often, the fluctuations should lessen .
But by doing only a small one per week, you allow acidification to to build up so much by the end of the week, that the new tap water with high pH (and more buffers) is drastically different, and can be a shock.
But lets say you do three 30% water changes per week. Each time time you are adding buffers that help bolster pH, and cut down on acidification, so after a while help maintain a more stable environment.

 

[Pomatomus]

My suggestion is to mix your tap water with some RO water to reduce the pH and soften it a bit.

Or add acid. Muriatic should work, or you could use a product like FlorinpH

 

[catfishacr]

If you do more frequent water changes, your pH probably won't fluctuate so much.
By adding water that buffers pH more often, the fluctuations should lessen .
But by doing only a small one per week, you allow acidification to to build up so much by the end of the week, that the new tap water with high pH (and more buffers) is drastically different, and can be a shock.
But lets say you do three 30% water changes per week. Each time time you are adding buffers that help bolster pH, and cut down on acidification, so after a while help maintain a more stable environment.

Thanks for the advice, I will do more frequent water changes and see if that helps.