Need help with water chemistry difficulties - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 8 Old 06-25-2009, 01:43 AM Thread Starter
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Need help with water chemistry difficulties

First I'll run down the nuts and bolts of my system.
90g/30g sump (system 6 months old)
100+ pounds LR
Good flow (two Koralia 4's, Mag 5 return pump)
Large recirc skimmer (Octopus)
refugium w/ rubble and chaeto (plenty of pods)
Not heavy on coral, but some SPS, LPS and soft corals
Livestock- 8 small to med fish, one RBTA, CUC
6x54w T5 lighting
RO/DI water, Seachem reef salt
10-15 gallon water changes every 1-2 weeks

Now, that's probably TMI, but I didn't want to leave anything out.

Temp 79-80
SG 1.024
pH 8.6
Ammo/trite/trate 0/0/0 (API)
Ca 360 (Seachem)
Mag 1050 (Salifert)
Alk 10 dKH (API)
phosphate undetectable (API)

My issues:
High pH. Consistently 8.6, verified with one "pen" meter, one controller probe and test kit.

Slightly high alk.

Mag: I have, for three days, been slowly dosing Bulk Reef Supply Ca and Mag, the Ca is climbing slowly, just like I want. The Mag (according to the BRS calculator) should come up 50ppm per dose/day, but it has not changed AT ALL. Still 1050 just like when I started. FWIW, I am actually getting good SPS growth even with these numbers.

It seems that most people struggle with low pH and alk; I have the opposite problem.
I have not been able to get any info on how to address these problems... helpful people have pointed me to articles that would be great were I a chemistry major, but I can find nothing for non-MENSA members at all.

Any water gurus have any helpful hints on where the root cause may be? The pH is the largest concern to me.

Thanks in advance!
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post #2 of 8 Old 06-25-2009, 06:42 AM
onefish2fish's Avatar
how old is the test kit? what have you been dosing for alk? mag can take awhile to climb to where it should be but once its there its easier to keep it at its desired level.
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post #3 of 8 Old 06-25-2009, 06:46 AM Thread Starter
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Originally Posted by onefish2fish View Post
how old is the test kit? what have you been dosing for alk? mag can take awhile to climb to where it should be but once its there its easier to keep it at its desired level.
Test kits marked API are 3 mo old, the Seachem and Salifert kit are less than six weeks old.

Maybe I should have been clearer... I've never dosed anything for alk, ever. My pH & alk are those levels without my help at all.
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post #4 of 8 Old 06-25-2009, 07:10 AM
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thats interesting. not even purple up? seems like that happens all the time.

your using RO but from where? your house? the store? test this before mixing it into your salt. when you make salt ( atleast 24 hours in advance ) test this too.
did you get a salt bucket? how much of it have you used already? when getting a new bucket of salt its always a good idea to make sure the lids on tight, roll it around on the floor for a few minutes then put it somewhere and try not to disturb it. this way all the minerals that settled to the bottom of the bucket can get mixed throughout.

also important, what time of the day did you test for pH? lights effect this.
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post #5 of 8 Old 06-25-2009, 05:33 PM Thread Starter
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Never used anything other than BRS Ca and Mag. I use RO from my system, 0 TDS readings. I use bucket salt, and have always mixed it before use. pH will test 8.6 pretty much around the clock (my fuge lights are on a reverse cycle).

My RO water reads crazy pH readings, but I've been told that that is to be expected because if it is truly pure there is nothing to properly measure. My new water tests 8.4 on average after plenty of mixing and aeration.

I'm pulling my hair out over this one. I do not want to have to dose vinegar or anything to deal with this; I believe that should not be necessary and may bring its own evils.
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post #6 of 8 Old 06-25-2009, 05:43 PM
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in my humble opinion, an Alk of 10 dKH is right on the money, that's where I try to keep mine locked at. Calcium is indeed a little low, but as you mentioned you are supplementing it and slowly bringing it up.

I don't have any advice for how to reduce your pH... the good (I hesitate to use the term "high") Alk level is likely helping to keep the pH up where it is, though why it raises from 8.4 to 8.6 once you add it to your tank, I don't know. But its not surprising to me that your pH isn't falling given your Alk level (which is usually a good thing!)

As for Magnesium, I've had good experiences using Kent Marine Tech M to raise and maintain my Magnesium level. Similar to what you described, it quotes a certain ppm raise in Mag each time you dose it, and when I was first raising my Mg up to where I wanted it to be, it went right up like it was supposed to. Now, I just dose once a week or so to keep it up, and have not had any issues since I started using it many months ago.

"To an optimist, the glass is half-full;
to a pessimist, the glass is half-empty;
to an engineer, the glass is twice as big as it needs to be"
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post #7 of 8 Old 06-25-2009, 05:56 PM
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if its 8.6 around the clock i would personally leave it stable but thats just what i would do.
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post #8 of 8 Old 06-25-2009, 06:05 PM Thread Starter
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Thanks. Now if I can get rid of the stinking dinoflagellate that cropped up hard a couple of days ago...

(Not related to the params, these were like this long before the dino outbreak... added one piece of LR that looked clean under PCs but went APE under my T5s. My turkey baster is getting worn out.)
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