Storing mixed salt water questions

[bobz]

I keep about 40G of mixed replacement salt water for water changes in a closed brute trash container with powerhead and heater. Usually, it only last a week but this batch has been mixed for over two weeks. I was going to do a water change last night on my 70G so I checked the pH before I did anything and it was low, 7.9, so I added some reef buffer and raised it to 8.4 last night. I covered it back up and turned the power heads back on. I checked again this morning and the pH had dropped back to 7.9 overnight. Why does this happen? I don't usually worry about the the pH of the replacement water when I mix up a new batch as it is pretty close to my tank water. This just confused me and I am not sure what to do with the new water. Use it, toss it, make a new batch? I think I will test this batch for calc, alk and ammonia to see what those readings are before I do anything with it. Any body else have an idea why this happens? I used to keep an airstone in the mixing container but I stopped. I wonder what effect that would have on the pH. I'll try adding one back in and see if anything changes.

BZ

 

[jaustin]

<span style="color: black"><span style="font-family: Verdana">The water is just saturated in CO2. The buffer is not a good fix, that will just temporarily raise ph and like you observed the PH just returned. However test your ALK in that water because it surely has risen from the buffer and has not fallen. Alk buffer is something that should only be used for alklinity and not PH and it should be added slowly at that to avoid calcium precip.

A ph of 7.9 is still fine. I would not worry about it but you can inject air into it with an air stone. Use a fresh air supply from outside and you'll bring the PH up within a few hours.</span></span>

 

[oz]

Hey Bob - create a smaller batch of new salt water and test after 48hours to see what the PH is. If it's 7.9 then you know it's not the time it spent in the Brute and most likely your salt. If it's 8.3 or so then you're probably right, lack of oxygen in the closed container. Another option to the airstone is point the powerhead up to break the surface of the water while mixing, that might help. I use a Mag 5+ to make sure there is a lot of surface disturbance.

 

[bobz]

thanks guys, I agree with the buffer comment... just surprised that the pH would swing back down that quickly. I did test the ALK and it was at 8 dKH. I don't have a problem with the low pH readings other than the fact that it was so quick to drop which surprised me. I have an air stone in the brute now and will let it run a couple of hours. Now I am more curious than anything else, to see what effect it has.

 

[bobz]

ares;340686 wrote: PH is for the most part, a property of the dissolved oxygen.

you could dump the whole can of buffer in there, but without dissolved oxygen, itll drop.

I have to keep going back to Randy Holmes-Farley's discussion on reef chemistry when ever I get in to these type of issues with alk and pH.

 

[jaustin]

you'll get it though. It will soon be second nature. Do you have any shots of your tank? I don't remember seeing them and I would like to see what your setup looks like.

 

[oldschool52]

I usually mix up 2 - 3 5 gal buckets 24 - 48 hrs before a water change. I put a small pump in each busket and a heater. I test s/g, ph, ammonia, and temp before doing water change. I do keep 5 - 10 gal of ro/di water all the time for top offs. The only reason I check ammonia because I had some trash salt a few months ago that crashed my tank.(got it on sale) I have been using IO salt for 35 years with no problems but bought this other salt on a whim. I am using IO reef crystals since I have reef tanks now and not fish only.

 

[bobz]

JAustin;340698 wrote: you'll get it though. It will soon be second nature. Do you have any shots of your tank? I don't remember seeing them and I would like to see what your setup looks like.

:yes: You would think after a couple of years (this time) it would start to sink in... guess my brain is full.
BZ

 

[oz]

bobz;340727 wrote: :yes: You would think after a couple of years (this time) it would start to sink in... guess my brain is full.
BZ

Time for a water change. haha

 

[corigan]

I leave saltwater sitting in 5 gallon jugs for weeks and use it with no ill effects. We had a conversation on this not too long ago in another thread.

 

[wbrown]

I do 32 gallons at a time, my source water Ph is 7.0 , after adding salt and mixing it's still 7.0. Agitate, add air, it may come up some, but well under 7.7.
Adding buffer does not seem to help, goes up for a bit, then slides back down. I've noticed a lot of precipitate too after dosing with buffer, but the calc is 420..
I usually decant the water for 8 hours after filling the brute as a precaution, we are on a DEEP well. I'm stumped as once it hits the tank, ph comes up to 8.0-8.3 and is stable.. skimmer maybe?