Ph dropping?

[Bones8d]

For some reason lately after the last 5 water changes of 40% I have a drastic drop in ph and takes a few days to stabilize back to normal which was always around 6.6 I can't for life of me figure out why. At 6.6 I used to inject co2 and like normal the ph would drop a little then would shut off with my controller. But when I noticed the ph was low after the water change I completely shut down the co2 and have been running an airstone since. My tap ph aged 24 hrs aerated is 7.0. After I do a water change the ph immediately rises to 6.8 but within an hr it will drop to 6.5 and so on untill it steadies at 5.6 or so then rise again. But by that time I'm due for a water change and the cycle starts over again. For reference my
KH is 4
GH is 6
I have 2 large pieces of driftwood which have been there for 3 months
Can anyone tell me what has changed in my tank to affect the ph in this manner?
Thanks

[jimg]

What are you using to test ph? kh 4 should not let ph fall that fast,driftwood will not do anything.

[jimg]

one more thing, when you drain the water from the tank is the probe from the ph controller out of the water possibly letting co2 in during wc's?

[Bones8d]

The probe is exposed but I have tested my ph with a API kit as well and it's accurate to what the controller is displaying.
Also I just remembered before that water change where all this started I remembered putting in 2 tablespoons of Epsom salt for my bloated discus. Could that be doing this?

[jimg]

epsom salt raises gh but has small impact on ph

[Bones8d]

Its been 5 hrs since my water change and the ph dropped from 6.8 to 6.2 so far

[leeishom]

id add one soup spoon of crushed coral for each gallon. add in a mesh bag in the canister or hang it around the edge of tank.

[waj8]

I don't think your KH is accurate. It's probably very low and Nitrification is lowering your pH. Your KH appears to be actually less than 1.0

[Bones8d]

I use the API test kit for my KH as well. The kit calls for 1 drop untill the test tube is yellow, and I'm sure it's at least 4 and even at that it's not super bright yellow.

[brewmaster15]

Have you added livestock or changed/increased your feeding regime?

-al

[Bones8d]

No everything has been exactly the same except for adding the Epsom salt and praziquantel liquid for my discus. No new livestock or different feeding habits

[jimg]

I know you said you checked with ph drops, but how old is the ph probe? Are you also sure about the aged water readings?

[Jhhnn]

I'd suggest that there may be a buildup of organic material in the tank. Nitrification lowers pH to a certain point, then nearly quits because pH is too low. Adding fresh water of higher pH stimulates nitrification, and the cycle repeats. Live plants tend to mask the effects on other water parameters.

[Bones8d]

Yes the tests of my aged water is accurate. It's at 7. But what do you suggest to cut the nitrification process down, a real heavy cleaning? I would also like to add after it dropped to 6.2 last night it's at 6.4 now and climbing still. So it never went down as low as before in the mid 5 range which is really confusing me now.

[jimg]

How many fish and what size tank? How often do you do the 40% wc's?

[Bones8d]

I have 4 discus 2 angels 2 bushynose 2 clown loaches 10 cardinals 2 Siamese algae eaters in a 55 gallon and my 40% water changes are every 3 days

[jimg]

A little heavy on population but not too bad, what size filter and how often do you clean the sponges/pads floss etc?

[waj8]

Either your pH reading is wrong, or your KH reading is wrong or there is another source of alkalinity in your tank. If the KH kit is measuring carbonate then your water won't be a pH of 7. Nitrification also won't drop the pH like that if your KH is 4. Likely explanation is that you have almost no carbonate and the test kit is measuring another source of alkalinity. Possibly the pH measurement is wrong but that would not explain the drops in pH. Your water acts exactly like it has almost no carbonate. Seems a little dangerous to me.

[jimg]

But he says it drops within and hour and then rises again. with low kh it would not rise back up. unless something else added to water.it would continue down due to nitrification.

[waj8]

I think I would expect that. If the change water is low in carbonate, which is indicated by the pH of 7, and then added to an acidic environment the little carbonate in the water would be eaten up by the acid. This will release CO2 into the water column which will then start to off gas. This raises the pH. Once this process is complete, the nitrification process starts over and the pH gradually drops again. Check the KH of the tap water or look for a water analysis for the tap water. The problem is likely in the change water and not the tank.

[jimg]

I think I would expect that. If the change water is low in carbonate, which is indicated by the pH of 7, and then added to an acidic environment the little carbonate in the water would be eaten up by the acid. This will release CO2 into the water column which will then start to off gas. This raises the pH. Once this process is complete, the nitrification process starts over and the pH gradually drops again. Check the KH of the tap water or look for a water analysis for the tap water. The problem is likely in the change water and not the tank.

Once this process is complete, the nitrification process starts over and the pH gradually drops again.

I agree with all, but he says the ph rises again, not drops.
And the nitrification process does not stop at 5.6 ph

[waj8]

"After I do a water change the ph immediately rises to 6.8 but within an hr it will drop to 6.5 and so on untill it steadies at 5.6 or so then rise again."

I still think he has very little buffering in the tap water and almost none in the tank. pH is very unstable at such low carbonate levels and can be affected by almost anything. The clue is in the the aerated sample of water only being pH 7. It should be higher than that. If the KH were really 4 then the the pH would be like 7.6 not 7.0. I would test the tap water KH. I would double check the tap water pH. I would put the driftwood in a bucket of tap water and aerate and test the pH. If the pH and KH are certain to be accurate then I would want to know what is in the tap water to make it act so abnormally.

[jimg]

Yeah i see what you mean. My Kh is 4 but my ph is 7.5 before aging and 7.8-8.0 after. the thing that's not sinking in to my "thick head" is if he ages it and co2 is off gassed why would the ph drop then climb again? wouldn't there have to be almost no buffers?
I can see why it would drop in a few days, but not hours unless co2 is leaking?
could it be fertilizers added for plants?
Don't mind me I am thinking as I write instead of thinking then writing!

[Bones8d]

I thank you guys for the help I'm just getting home from work now and I'll check the KH of my tap and let you guys know what it is also I don't know if you read what I wrote before but the ph has been rising faster today and last night it only dropped to 6.2 before it started to rise again.

[waj8]

Y
Don't mind me I am thinking as I write instead of thinking then writing!

I am just speculating. There is not enough info to go on. I think you are thinking very well.

[waj8]

Y
Don't mind me I am thinking as I write instead of thinking then writing!

I am just speculating. There is not enough info to go on. I think you are thinking very well indeed.

[jimg]

trying to at least!

[Bones8d]

Ok so far today my ph now is at 6.5 and I tested my KH out of tap and it's 4 for sure but should I have to age and aerate that as well?

[waj8]

I am running out of ideas. The KH won't change with aeration. You can double check the pH after aeration. If it is still 7 that means the the pH/KH/CO2 relationship is broken or you have a bad test kit. You would have to check your test kits against a reference. You would also have to find out the contents of your tap water.

[jimg]

Maybe try a little baking soda and see if it stabilizes better? I know you said you checked the ph but I know when one of my probes is going bad i get strange readings.

[Bones8d]

I know I'm lost for ideas as well. My probe is new maybe a 2 months old and as for the test kits, my ph test kit is giving the exact reading on my controller which pretty much rules that out. Not sure what to do anymore. It's amazing something can change what's happening in my tank so quickly. What do you guys think of a larger water change? Like maybe 80%?

[Bones8d]

Also in the middle of all this I have a sick discus, spitting out food and kinda of shaking her head. So far I tried prazipro for 2 treatments. She's hungry and wants to eat but you can tell she's hurtin when she does.

[jimg]

Definitely up the wc's see what happens. try a little baking soda see if that stabilizes the ph. maybe raise the temp see if it eats.

[Bones8d]

Thanks alot For Everyones help