Need some help with water chemistry.

[nymike23]

Hi
Im hoping that someone could help me out with my water issue. My tanks been humming along smoothly for the past year until 2 weeks ago. Had a accident and lost my 10g fuge. Long story short everything has been going ok with exception of one problem, my Buffering capacity. Starting about last week I have noticed a drastic swing in my ph at night.. I know some is normal but I swing from about 8.3+ around lights out to about 7.8 in the morning. I am also having trouble maintaining my Alk. Ive been doing 10% WC weekly and I havent seen any results. I added a new pwr head for circulation and better gas exchange thinking of a higher carbon dioxide build up, even did the aeration of a Gal of water test which showed no CD buildup.
Ive tried buffer, no good and all the other obvious stuff. I just ordered a Magnesium test to check if the tank is dificent in that. I even added a DIY Acua clear 110 mini fuge. Below are a list of my most recent perameters

SG: 34/36
PH: see above
Alk- 5-6 dKh -- cant maintain a higher level than this for more than a day or two
Cal: 460-500- Havent added a Cal. supplement In about two weeks.
Phosphate- undetectable
AMM: 0
Nitrates- Trace if any

Please feel free to ask me any other ?s if I forgot anything.
Thanks

[FishinInTheDark]

What brand of salt are you using?

[nymike23]

I have been using coralife since day one but the local store was out and Ive been using instant ocean.

[FishinInTheDark]

What brand of water tests are you using? How old are they? I find the results suspicious because buffering your alk will also drop your calcium reading. Yet, you continue to buffer and the calcium is still extremely high. I'm wondering if your water isn't closer to normal than you think, but you're getting bad test readings.

IO is generally slightly low in Ca/Alk, but closer to balanced. Have you tested your fresh saltwater before putting it into the tank? If it's normal, I would suggest upping your water change regimen.

I'm just stabbing in the dark, but we'll get to the bottom of this!

[nymike23]

OK
I use hagen and Aquarium Pharm. test kits. The LFS sell seachem kits but want 25$ a pop and forget about the price for Salifret kits. As far as age they are about 3 months old. My water change water measures out at a PH of 8.4 with a Alk of 10 DKh. Matter of fact I changed the water yesterday and my Alk is back down to about 6 Dkh today. It was 9 after the water change. Just for informations sake I do use distilled water for all my WC and top off needs.

[FishinInTheDark]

I think that if you're getting normal readings off of your fresh saltwater, the test kit is probably good.

What was the effect on calcium? Did it come down? I know you're not dosing calcium anymore, but what are you using to buffer the alk? It just doesn't make sense that the alk drops after you get it correct. Even if it were binding up with the calcium and building up on your pumps and heater, the calcium would be falling. Even if you were raising alk too quickly and it was precipitating out of suspension with the calcium, the calcium numbers would be falling.

Anyway, I'm wandering aimlessly now; what buffer are you using?

[nymike23]

I have been using Kent superbuffer at 5ml a day on a slow drip. MY calcium is still high 460 according to test results. Luckly everything in my tank is doing ok but my yellow leather seems to be annoyed with this problem. He has'nt opened up for the past two days. Yesterday after my water change he opened up nicely, today ditto. PH last nigh was 8.4 this morning 7.8................ Im lost!!!!!!!!! :uzi:

[FishinInTheDark]

I'm just completely lost on this one. I understand why the pH fluctuates with the chemistry so far out of balance, but I can't figure out what's happening with your alkalinity. A teaspoon a day should get your 20G tank there relatively quickly. I'm going give a shout to Mike, who is our resident water chemistry expert. I believe that he is busy this evening, but I'm sure it won't take too long for him to swoop in and save the day.

[MikeS]

I'd suspect that the high level of Ca is keeping the Alk down....when you have a large imbalance one direction or another, it can be difficult to get the low level up, no matter how much you add.

At this point, your best bet is to start a series of water changes with properly balanced water....continue them until you get your parameters back inline....

MikeS

[nymike23]

here are my Most recent results
Alk 9dKH
PH 8.1
CAL 480
I guess Ill start doing water changes. Any reccomendations on the frequency and how much?

thanks for the help

[MikeS]

10% every other day will be fine as long as you have the temperature and SG close, you'll have no problems....

what is happening here is that your calcium is so far out of balance with your alkalinity that adding addtional alkalinity isn't going to raise it. On that note, I'd suggest also no longer using the Kent alkalinity suppliment, as these tend to to be higher in borate salts than you are going to want long term. Use baking soda.

Here's an article on calcium/alkalinity balance...

http://www.reefkeeping.com/issues/2004-12/rhf/index.php

and a link to Randy's articles....he has quite a few on the topic...

http://www.reefcentral.com/forums/showthread.php?s=&threadid=102605

hope this helps...

MikeS

[FishinInTheDark]

Thanks for bailing me out, Mike! :)