Acidic Water =(

[Noahs ark6]

Hello

I'm contemplating setting up a reef tank somewhere in the near future, but i have a question.

My tap water is ph 6.5-7. I'm aware marine tanks prefer/need a higher PH, so am i still able to keep a marine tank (i dont want to use chemicals)?
Does the live rock and sand naturally buffer the PH? but then when doing a water change wouldn't that alter the PH again???

Thanks

 

[lljdma06]

Hello

I'm contemplating setting up a reef tank somewhere in the near future, but i have a question.

My tap water is ph 6.5-7. I'm aware marine tanks prefer/need a higher PH, so am i still able to keep a marine tank (i dont want to use chemicals)?
Does the live rock and sand naturally buffer the PH? but then when doing a water change wouldn't that alter the PH again???

Thanks

You'll have to use chemicals anyway. Not necessarily to up the pH as yes, the sand and rock do have a buffering capacity, but you'll probably have to use chemicals to remove heavy metals, ammonia, nitrates, chlorine.

I use RO/DI water. Here is an excellent explanation from our Resource center regarding the pros and cons of tapwater.

http/www.fishforums.net/index.php?/topic/381737-so-you-want-a-sw-tank/page__view__findpost__p__3201649

In my experience, it depends on the corals you are keeping and where you live. I have a lot of friends who keep SW in Miami. The ones with the most successful mixed reefs or those who grow the small polyped stony corals (acroporas, stylos, etc) will tend to us RO/DI water. Many of my friends using tapwater struggle with these corals, yet can do the large-polyped stony corals and soft corals without a problem. Some sps corals may also work, but they won't grow as much. A lot depends on the growth habits and particular desires of the coral being grown too.

L

 

[Noahs ark6]

I meant chemicals to alter the PH

Thankyou, that was helpfull.

Would adding some crushed coral to the filter have the same effect in a marine tank as it does in a tropical tank?
If so, how often would it need replacing?

 

[Donya]

Does the live rock and sand naturally buffer the PH?

Yes, but within limits and also slowly. If you are putting in water with a too-low pH at each WC, you may still struggle to keep the pH where you want it. It's not a sw-specific condition; the same would be true in freshwater tanks with higher KHs.

but then when doing a water change wouldn't that alter the PH again???

You really need the incoming water to be at or very close to your target pH for the tank for that reason. Top-offs are a bit different since the volume is small; as long as the buffering capacity of the incoming water is weak (like RO) then a different pH is ok (RO would have a pH of 7.0 for topoffs). If the pH of incoming water for a WC is too low, you would need to buffer it up with something like sodium carbonate (not bicarb) to avoid slowly dragging down the pH of the tank over time. However, depending on how much it takes to get the pH up, doing so can also screw up other parameters. A small tweak is usually fine, but salt mixes in general don't behave well with large doses of buffers.

On the other hand, if your tap is actually pretty soft despite being mildly acidic, the salt mix might be fine and still give you a pH in the 8.0-8.4 range. 6.5-7.0 is a big range. Does your tap fluctuate over time in that range, or is that the most accuracy you can get out of your kit? Have you tried a mix? If you don't have salt yet, you can usually get small bags of salt that will only mix 5gal or so and then do a small test with just a gallon before sinking a bunch of money into a giant tub of the stuff.

 

[Noahs ark6]

Does the live rock and sand naturally buffer the PH?

Yes, but within limits and also slowly. If you are putting in water with a too-low pH at each WC, you may still struggle to keep the pH where you want it. It's not a sw-specific condition; the same would be true in freshwater tanks with higher KHs.

but then when doing a water change wouldn't that alter the PH again???

You really need the incoming water to be at or very close to your target pH for the tank for that reason. Top-offs are a bit different since the volume is small; as long as the buffering capacity of the incoming water is weak (like RO) then a different pH is ok (RO would have a pH of 7.0 for topoffs). If the pH of incoming water for a WC is too low, you would need to buffer it up with something like sodium carbonate (not bicarb) to avoid slowly dragging down the pH of the tank over time. However, depending on how much it takes to get the pH up, doing so can also screw up other parameters. A small tweak is usually fine, but salt mixes in general don't behave well with large doses of buffers.

On the other hand, if your tap is actually pretty soft despite being mildly acidic, the salt mix might be fine and still give you a pH in the 8.0-8.4 range. 6.5-7.0 is a big range. Does your tap fluctuate over time in that range, or is that the most accuracy you can get out of your kit? Have you tried a mix? If you don't have salt yet, you can usually get small bags of salt that will only mix 5gal or so and then do a small test with just a gallon before sinking a bunch of money into a giant tub of the stuff.

Hi

No, thats the best i could get with my test kit.
So the salt actually raises the PH?
I'll ask my LFS if i can buy just a cup full to see what it does to my water.

Thanks for the reply, very helpfull

EDIT- Sorry another Q- Would filtering my water through an RO/DI unit reduce the hardness and PH too much and cause unstable water? or, because my PH is low, not affect the hardness/PH?
Thanks

 

[Donya]

So the salt actually raises the PH?

A salt mix isn't like table salt or the freshwater salt stuff that you put in with things like goldfish and mollies. It's like the seawater version of instant mashed potatoes: just add water and you get all the ions and everything it's supposed to have in the right concentrations. Obviously NaCl is going to be a big part of that, but it's not the sole component. There will be a lot of other compounds in it too that provide calcium, magnesium, and so on. Ion concentrations change pH, so you should get a pH of 8.0-8.4 depending on the salt brand and exactly how pure the water was. If the water going in isn't very pure, the pH could end up elsewhere on the scale.

Would filtering my water through an RO/DI unit reduce the hardness and PH too much and cause unstable water? or, because my PH is low, not affect the hardness/PH?

I'm not sure what you mean by unstable water. The whole point of RO and RODI is to remove dissolved solids and ions to give you pure H2O, which has a pH of 7.0. Mix that with a store-bought salt mix and you get seawater. Mix the same salt mix with water that has a high KH and you can even end up with calcium carbonate to precipitating out in a snow-like way. That sucks calcium out of the water and gives you goofed up seawater instead of as-intended seawater. It doesn't take a particularly high KH to cause that either; a tap KH of 4-6dKH has done it for me.

Regarding the low pH, it is possible (although rare) to have low-pH water with a problematic KH for a salt mix. You need to know both about the tap. If you mix a small batch of salt though and see calcium carbonate precipitate out, you basically have your answer there too and will need to use RO or RODI.

 

[lljdma06]

So the salt actually raises the PH?

A salt mix isn't like table salt or the freshwater salt stuff that you put in with things like goldfish and mollies. It's like the seawater version of instant mashed potatoes: just add water and you get all the ions and everything it's supposed to have in the right concentrations. Obviously NaCl is going to be a big part of that, but it's not the sole component. There will be a lot of other compounds in it too that provide calcium, magnesium, and so on. Ion concentrations change pH, so you should get a pH of 8.0-8.4 depending on the salt brand and exactly how pure the water was. If the water going in isn't very pure, the pH could end up elsewhere on the scale.

The comparison to instant mashed potatoes is awesome.

I just had to tell you.

L

 

[Noahs ark6]

So the salt actually raises the PH?

A salt mix isn't like table salt or the freshwater salt stuff that you put in with things like goldfish and mollies. It's like the seawater version of instant mashed potatoes: just add water and you get all the ions and everything it's supposed to have in the right concentrations. Obviously NaCl is going to be a big part of that, but it's not the sole component. There will be a lot of other compounds in it too that provide calcium, magnesium, and so on. Ion concentrations change pH, so you should get a pH of 8.0-8.4 depending on the salt brand and exactly how pure the water was. If the water going in isn't very pure, the pH could end up elsewhere on the scale.

Would filtering my water through an RO/DI unit reduce the hardness and PH too much and cause unstable water? or, because my PH is low, not affect the hardness/PH?

I'm not sure what you mean by unstable water. The whole point of RO and RODI is to remove dissolved solids and ions to give you pure H2O, which has a pH of 7.0. Mix that with a store-bought salt mix and you get seawater. Mix the same salt mix with water that has a high KH and you can even end up with calcium carbonate to precipitating out in a snow-like way. That sucks calcium out of the water and gives you goofed up seawater instead of as-intended seawater. It doesn't take a particularly high KH to cause that either; a tap KH of 4-6dKH has done it for me.

Regarding the low pH, it is possible (although rare) to have low-pH water with a problematic KH for a salt mix. You need to know both about the tap. If you mix a small batch of salt though and see calcium carbonate precipitate out, you basically have your answer there too and will need to use RO or RODI.

Oh, I was under the impression that filtering water through an R/O unit lowers the Ph of the water, and the if the PH and hardness is too low, there could be fluctuations in PH, but i know otherwise now, thankyou very much
As above, i'll go to my LFS and ask if i can buy just a cup of salt, thanks