Hard Water with lower pH

[Caroleinwv]

My tap water is TDS 300+. However, my pH is 7.4-7.6 rather than more Alkaline. Is there some mineral component that drives this? I don't think it is a problem but I am curious. 

In my tanks with plants, peat, leaves my tanks have dropped into acidic ranges while getting ridiculous TDS with water top- offs. That did create problems.

[Ben C.]

Following this, because mine is TDS 300+ and my pH is 6.8, if not less. Buffer is lower though. Doesn't seem to cause issues to my knowledge so far, but seems super weird.

Edited June 5, 2021 by benchilton

[Caroleinwv]

This sounds very similar to my own water. I had a broken wrist and shoulder surgery over the winter and could only do water topoffs to tanks. Things were OK,  then they were not with plant and fish die offs. With ApI test kit, water looked OK. Then got TDS meter. I got readings over 1000 ppm. Then used API hardness tests and readings were over the top. By then my right arm was better and I started doing water changes with distilled water and bought an RO system. Constant testing as it can be tricky to get TDS down without dropping kh buffer too far, too fast. I am finding that fish/ and most plants are Ok once I got below TDS of 800 ppm. Stem plants seem to hate this water the most. Anubias do not care. Crypts are OK but not as tolerant as Anubia.

I live in Northern WV, about and hour SW of Pittsburgh , PA. From my college Chem days, I know we do have high iron content and am wondering if this is a factor.

[Isaac M]

Hello @Caroleinwv, have you read about old tank syndrome before? Usually if top-offs are being done on an aquarium, it introduces more minerals into the aquarium since they do not evaporate out. You either need plants and/or a water change to remove the minerals from the aquarium. TDS readings are tough because they do not specifically measure for one known compound in the water. I think it would be helpful if you found your local water report online and reviewed that. Mostly anything, even the iron as you mentioned will increase the TDS reading. And iron will not show up in your ph, gh or kh test. 

Your TDS will also increase(and can increase significantly) if you add liquid fertilizer into the water since they are meant to add nutrients into the water. 

Do you have your test result for your gh? kh? 

[Caroleinwv]

Thank you Issac! Yes, I understand Old Tank Syndrome and have painfully lived it due to my surgeries and inability to do water changes. I had to add water with a pitcher as I could not manage buckets or even a python due to not having use of both arms.  My tanks are all planted but don't absorb minerals fast enough to balance against evaporation.

I guess my point is that I did not see an expected pH response as the mineralization climbed.  

I don't routinely add ferts. I tend to do that as indicated by low nitrate.

My question was due to wanting more understanding toward causation of lower pH when one may expect an alkaline mineralized water.

 

Again, thank you for your input!

Edited June 5, 2021 by Caroleinwv

[Isaac M]

@Caroleinwv were you expecting to see an increase in pH because of the increase in TDS?

pH typically only increases as kh increases. If you are expecting your kh and ph to increase because you are topping off, it is possible that the kh you are adding into your aquarium is not enough to keep up with the kh being “used up” by the nitrogen cycle. This can lead either to a lowering of ph or it can stay the same if the kh added by topping off is balanced with the kh being used up by the nitrogen cycle.

I would test for kh specifically however to get a clearer picture. I would test the kh of the aquarium and the kh of the tap water.

I apologize if I am still not clear on the question exactly. 

I am sorry to hear about your surgeries and the difficulty it adds to your hobby. I would try adding a top to your aquarium if you do not already have one to minimize evaporation. Topping off with a mixture of RO water (I think you mentioned you bought a system) and tap water may help as well. 

[Caroleinwv]

On 1/21/2021 at 9:27 AM, Fish Folk said:

Thank you Issac!

That explains a lot and pretty much connects the dots. In slowly working my TDS down I had noted that I still had a high TDS while being in danger of losing my buffer kH so alternatively have been mixing.

I now understand my mistake in relying on pH to indicate "soft water".

I really appreciate your help! So much to learn!