Quick, what was your alkalinity last week?

Sk8r

Staff member
RC Mod
...and is it trending down, or is it steady from the week before?

THat really is an important thing to know. New tanks can be quite volatile, and low alk can produce cranky or sick fish, and make corals fail.

A tiny notepad and a pencil is an important part of your fish kit. Test, and write those things down. I've been at this for years, and while I can give you a general answer without a notebook, I can't give it accurately without double-checking. A .1 fall IS significant, because once it starts down, it goes down and down, and you will soon see an unhappy tank.

Many tanks, even with faithful water changes, still have to do some supplementation of alkalinity buffer. Iffy alkalinity is one big reason new hobbyists have troubles---even more so if you have corals.
Your 'good' range is 7.9 to 9.0. And 8.3 is a good middling point to sit on. If it goes low, it can affect your fish. If it goes way high, it's not so bad, but it can crud up your hoses and pumps.

For those struggling to keep alk up, check your magnesium reading as well. If it is below 1200, your alk will start to fall. A little dose of magnesium, up to 1350, and your alk readings will be much more stable. Never guess. Always test. And write it down, with the date.
 
I am glad you posted this, because I have something going around in my head. I try to keep my ALK at about 9, but my water seems to love hanging out around 7.5. I know the importance of maintaining a higher ALK, but I also know that stability is more important than chasing numbers. The two thoughts kind of have me in a pickle. The thing is, I test every week, and some weeks it's fine, dropping to about 8.5, then others it's 7-7.5. It has never been less than 7, which is why I think that's my waters natural state.

I feel like the constant drop and rise of ALK is more damaging than keeping a lower ALK?

I don't test for MAG, so maybe I should start, but then that is just one more number to chase. What's more important, numbers, or stability?
 
IT depends on what you're trying to cultivate. It's a bit low. Magnesium above 1200 is what stabilizes alk and cal. If you bring the mg above that level, your alk should be willing to hold at, oh, 8.3 or 7.9, or whatever you decide to set. Magnesium is in this sense the stabilizer. Calcium is the third part of the triad, which I like to have at 420, but it can be higher: I keep stony coral, which likes 420.
 
I tried to add a Birdsnest, but that's about as stony as I will probably get. Before that, I was very much a part of the "stability is grater than reaching numbers" school of thought. After that experience I decided to try to keep my ALK at 9 or 10, but in doing so I think I have lost stability. A swing from 8.5 to 9.5 once a month or so is reasonable. Dropping to 7.5 in a week and then playing catch up, is not. I don't think.
 
A birdsnest is an sps, which is as a class a fussy stony. Hit 8.3 alk, 1350 mg, and 420 cal and it would be a lot happier.
 
I keep one of those small spiral notebooks and always write all my test results down, any dosing done and what/when new equipment goes online and livestock added. I even note when I have to adjust my heater-lol. My alk stays pretty steady but I'm using IO salt and my mag can run as high as 1500; especially right after a water change.
 
A birdsnest is an sps, which is as a class a fussy stony. Hit 8.3 alk, 1350 mg, and 420 cal and it would be a lot happier.

Alright. So don't give up. Keep working on getting my ALK higher, and then work more on keeping it there. Thanks. That's just been worming in my head for a while.
 
Also! do not dose alk and cal within 8 hours of each other, (makes a snowstorm and does no good) and do not bother to test your water just after dosing. It won't read right. Wait until your latest dose of whatever it is has had 8 hours to dissolve and work.
 
So you say dosing should be in one go? I am trying to spread my alk as far out over the day as possible. Like this, it should vary less. Alk is dosed during the full hour and calcium on the half hour. Now granted, I only need to dose very little as I have mainly softies and a few LPS in a 40 gallon.

Would you recommend me to dose only once a day and keep calcium and alk further apart?

Also, I dose them directly in front of a pump (I have no sump) so mixing should be optimal and I fear only little interaction of the freshly dosed liquids as it is only 1ml at a time.

Thank you for all the help you share on the forum!

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I put a corrective dose of calcium in all at once, at the downflow end of my sump, but I limit how much per day, according to the product instructions. I also use kalk in my ATO reservoir, so it's rare that I have to dose at all, except magnesium. Magnesium falls very, very slowly. Once it goes below 1200, then both alk and cal become unpinned and will fall rapidly. In this way---I only have to dose ANYTHING but mg maybe, oh, every 3-6 months, because the constant kalk (pickling lime) supply keeps everything level but the mg.

When you are starting out to 'level' the parameters, you dose mg first, then alk, then cal.

If you put kalk into your ato reservoir, AFTER 'leveling' your parameters, and IF you keep adding kalk and water, so the reservoir never runs out of kalk or runs dry, you just test mg weekly and so long as the MG stays up, that kalk in your ato feed will supply everything your tank needs except its routine water changes. IT's the way the ocean does it: the acidity/alk level it maintains (around 7.9 to 9 or whatever) dissolves calcium from old dead coral and the oceanic vents, probably, keep pumping mg into the ocean, and it all stays proper for thousands of years.
 
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