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Alk, Calc, PH test


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I've been having low alkalinity issues in my 5 gallon, and my corals seemed to be suffering because of it.

It started when my candycanes began shrink up and the skeleton started to poke through the flesh. I had my lfs test my water because I had lost my alk test kit readings chart. It was really low, though I don't remember the reading now. I didn't test my calcium but I can only imagine that it was way high, since I have oceanic salt and was dosing seachem brand calcium as well. I decided to stop dosing calcium do some water changes and up my dosing of seachems "reef carbonate" (alk buffer). It worked a little because my candycane came back to life, but my blastomussa began to shrink up and show skeleton. When I had the lfs test my water a few weeks later, my calcium was on the high end of normal (450 or so) but my alk was still as low as it had been before. This is when I decided to buy myself a new calcium test kit, and get a copy of the alk reading sheet from my lfs, and run a small experiment.


first I mixed up some fresh saltwater (oceanic brand) and let that sit over night. after I had checked the specific gravity to match my tank's (1.024), I tested Ph, calcium and alk. These are all salifet test kits.


Fresh saltwater: PH 8.0-8.1

Cal 520-540ppm

Alk 7.7 dKH



So I established my main problem.... my fresh saltwater had too high of calcium and too low of alkalinity. I did a one gallon water change on my tank with the water, and stopped dosing everything... I only topped off fresh R/O.


The day after the water change the specs were like this:


Day 2: PHam 8

Cal 480-490 ppm

Alk 6.4-6.7 dKH


I know that PH changes through out the day, and that a low Alk would cause higher PH swings, so I noted what time of the day the PH was read. Unfortunately I was unable to check it that night.


I continued this for 4 more days, testing every other day. Here's the results


Day 4: PHam 7.8-7.9

Cal 470-480

Alk 5.4-5.8


(today)Day 6: PHam (10am): 7.9 PH (4pm): 8.4

Cal 450-460

Alk 4.8


at this point I stopped because my Alk had dropped below my comfort level and I didn't want to kill my inhabitants. also the PH swings are huge! from today 10am -4pm it went up about .5 and I am going to test again right before my lights go off at 8pm. My calcium has been slowly falling at about 10ppm per day, but my Alk has dropped nearly .5 dKH every day.


I've decided that no calcium dosing is necessary if I continue my weekly water changes, but I have already began dosing my Alk buffer again. Seachem recommends (for a 5 gallon tank) dosing 5ml to raise the alk 1 meq/L (my tank drops about .3-.35 meq/l perday) so that means if I want to stabilize that I need to dose enough to raise it .3-.35 meq/l and to raise it I want it to be more like .4 meq/l per day which means I need to dose 2ml of the product perday..... SO my topoff goes through a gallon of water in a little over 2 days, so by adding one capful (5ml) per gallon of r/o I should slowly begin to raise the alk.


that was a mouthful to even type. What does everyone think? does this sound like a decent method? I'm going to do another series of tests after my next waterchange and see if it gets better.

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yeah, i use the oceanic salt too...I really like it alot, but the alkalinity is a little on the low side. I just bought the seachem powdered "reef builder" to beef up the alkalinity. Im still kinda reading up on how much to add because it says half a teaspoon per 40 gallons. I guess i will just add 1/4 of a teaspoon and see what that does to my top off water

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i used to have the same problem, but since ive added more sps corals the situation has reversed. low calc/high alk. for my problem i was using kent superbuffer everyday.

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well, i know for a fact that the powdered version is much more stronger as if it is a pharmaceutical grade. I just added the first bit into my top-off water and into the tank this morning. In a few days Ill measure the alkalinity and see how it stands..

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yea, but that is just in the raw. You need some minerals added to the concoction to balance the alkalinity levels being raised. You raise the alkalinity, but other things begin to drop, such as calcium and magnesium. Generally, good "over the counter" addatives contain these additional minerals that would normally be depleted because of dosing.

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