Why's my pH so low?

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RickU
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Why's my pH so low?

Post by RickU » Mon Oct 17, 2011 1:01 am

I have a 40gal freshwater aquarium and the water has a pH that is consistently lower than the water I put in it. I tested tonight and the aquarium water is 6.7 while the tap water is 7.6, both of why are typical of what I usually find. I do 25% water changes every 2-3 weeks, so there's quite a bit of new water going in. I should point out that the water is from a well and it goes through a softener and nitrate reducer before it gets to the tap. Is that the issue? I find it hard to keep plants in the tank, although the issue there may be the low bio load I have in the tank (just a few inches of fish for the last year or so). Any thoughts on why the pH stays so low? And, if it's more hassle than it's worth to raise it to neutral, any suggestions for fish and plants that like a low pH?

Craig_
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Re: Why's my pH so low?

Post by Craig_ » Mon Oct 17, 2011 10:07 am

You might have a buffer in your well water that changes the pH as the water degasses. Try placing raw tap water into a jar/bucket and check the pH. Wait a few days and check the pH in the jar/bucket again. If there is a difference then you know the issue is coming from the water itself and not something in the tank.

Eyrie
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Re: Why's my pH so low?

Post by Eyrie » Mon Oct 17, 2011 1:49 pm

It's because the water is being passed through a softener. This will remove the minerals that normally act to buffer the water and prevent/delay acidification. Check the kh of the well water and compare that to the kh of the water whichyou add to the tank. I'd also recommend doing more frequent water changes to help replenish the kh in the tank.

It's not a major issue if you keep softwater fish.
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starsplitter7
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Re: Why's my pH so low?

Post by starsplitter7 » Mon Oct 17, 2011 5:37 pm

I agree, don't worry about the pH, if you have fish that like the pH low. My water is liquid rock. I live in Florida. High minerals, and my pH out of the tap is about 7.4. However the water in my tanks is about 6-6.7 pH and my snails dissolve. I know that the main reason my pH is so low is because I have too many dissolved organics in my water -- poop, rotten food, . . . so I do 25-50% water changes every 7-10 days. My tanks are over populated, but healthy as long as I keep my water changes up and lower my organics. My pH stays low though, but I have laoches, and catfish from south America, so no problems.

RickU
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Re: Why's my pH so low?

Post by RickU » Tue Oct 18, 2011 12:25 am

Thanks for the helpful info on this, guys. I had also thought about letting some tap (well) water sit for a few days and testing it, Craig, but haven't ever done it. That would be interesting.

I had to laugh at your comment about "liquid rock", Starsplitter. When we first moved into this house and had the Culligan guy out to test the water the reading he got was so high he was sure he had made a mistake and tested again. He claimed it's the hardest he's ever seen.

I appreciate everyone's suggestions that I not worry about the pH too much and just go with fish that don't mind it. I think that's what I'll do.

Many thanks,
Rick

Craig_
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Re: Why's my pH so low?

Post by Craig_ » Tue Oct 18, 2011 12:50 pm

Just curious, but what type of water treatment filters are you running? Just salt, or did you end up with greensand or potassium permanganate as well? If your water is that hard, I'd be surprised if the iron or maganese levels weren't high as well.

RickU
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Re: Why's my pH so low?

Post by RickU » Tue Oct 18, 2011 6:48 pm

Just salt, Craig. I've tested the iron level in the past (both chelated and free) and came up with 0. There is also a nitrate reduction system in the flow (same as the water softener but with a different resin), which also uses standard water softener salt. Not sure if that would help keep the iron levels low.

Craig_
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Re: Why's my pH so low?

Post by Craig_ » Wed Oct 19, 2011 11:01 am

Cool beans, I was wondering about what kind of treatment was already in place. I had hard well water (with a high alkaline buffer) and a few filter types growing up, and found that it was easier for me to buy a 5gal(19L) bottle of water every week or two and mix with aged well water for changes. It isn't ideal, but sometimes you do what you have to do.

Were I still on well water I'd probably look into a RO unit.

RickU
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Re: Why's my pH so low?

Post by RickU » Sun Oct 30, 2011 11:13 pm

Actually, Craig, that is something I was considering. We have an undersink RO unit in the kitchen and it wouldn't be that hard to tap into it to fill a container for the aquarium. If I did that, would I have to add anything back into the water before I added it to the aquarium? I assume some of the minerals in the water are actually beneficial to fish and plants.

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Re: Why's my pH so low?

Post by KittyKat » Mon Oct 31, 2011 6:21 am

RickU, have you looked specifically into softwater plants? Things like Vallis generally don't do that well in soft water, but you should have better luck with something like Cabomba, for example.

pH of 6.7 isn't that low, but if it changes by so much, I assume your water is quite soft and poorly buffered (so low GH and KH), which is what would affect the plants.

While I do not recommend liquid buffers or any other serious messing with pH, it would be a good idea if you got liquid GH and KH test kits (some of these measure GH as permanent hardness + KH, while water suppliers measure GH as permanent hardness only) and maybe consider adding a small handful of mussel shells to the aquarium as a method of maintaining your KH in the long term, in between the water changes, so your pH doesn't crash.
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Craig_
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Re: Why's my pH so low?

Post by Craig_ » Mon Oct 31, 2011 1:21 pm

RickU wrote:Actually, Craig, that is something I was considering. We have an undersink RO unit in the kitchen and it wouldn't be that hard to tap into it to fill a container for the aquarium. If I did that, would I have to add anything back into the water before I added it to the aquarium? I assume some of the minerals in the water are actually beneficial to fish and plants.
There are additives/liquid fertilizers that specifically address adding trace elements back to RO/distilled water, but you may be able to successfully mix RO with your tap water and bypass something else to purchase.

I've seen a setup where a mechanical float switch was added to a bucket under the sink with the RO unit. The RO would pump into a container (think overnight), and when the water level hit a certain height the RO would shut off.

Myself, I now use a liquid fertilizer and I'm on otherwise raw municipal water. I have little experience with successfully growing a wide selection of plants, and I'm learning as I go.

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