Sudden ALK increase - Should I worry?

NigelRichardson

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Reef has been up and running for about 10 months, and a couple of months ago I started to dose (LPS / Softie tank right now) - primarily ALK, and a tiny bit of Ca / Mg to keep everything stable

I worked out that my ALK was dropping by 0.1 dkh / day, and have been dosing appropriately. All wonderful so far.

ALK has been stable in the 8.9 to 9.1 range (Some of you may be horrified that its not 100% stable, but for me - a noob - I feel like I'm getting there) for several weeks now

Standard 10% weekly water change (Aquarium Systems Reef Crystals - which I've been using since day 1) yesterday, and my ALK has suddenly spiked to 10 (Previous water changes didn't cause any spikes).

I didn't believe my Hanna checker so checked it twice, and confirmed with Aquarium systems test kit - its definitely 10...

Salinity was - and still is 1.025 - so its not like I added way too much salt or anything obvious...

Any ideas what could have gone wrong / if I should worry / what - if anything - I should do, or do I just wait and watch it slide down again over the coming few days?

All thoughts welcome - thanks for helping out a concerned relatively new reefer !
 

fachatga

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Don’t know what went wrong but I wouldn’t worry at all. Remember first that these kits can have 10-20% ranges of accuracy so we can’t ever really measure to tell if things are perfectly stable. So the real swing might not have been as big as you’re measuring. For my tank I don’t have a doser and need to put in about 0.5 twice a day to keep it stable. So in a sense it goes up and down about 0.5 a few times a day and I get great growth in lps and sps. Maybe I’ll do better when I buy a doser but I always think to myself that it’s possible to have a good tank without all the new technology. Which means alk will swing up to a daily dose and down every day if being done manually. So I don’t worry. Neither should you.
 
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NigelRichardson

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I've just done a Hanna Checker test - 24 hours after my sudden 9.0 to 10.0 ALK "spike".....

and it's dropped to 9.9 - which sort of confirms my hypothesis that this really did happen and now we're back to my normal / expected 0.1 dkh/day consumption...

I'm still very confused... How on earth can a 10% water change increase ALK from 9.0 to 10.0 ?
 

BostonReefer300

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Salt mixes aren't as "mixed" or homogenous as we'd like to think. Components of the mix can settle differently over time and sometimes things aren't mixed as well as expected at the factory. Therefore, every scoop may have a different composition---sometimes noticeable, sometimes not when you check your parameters. In any case, "keeping your alk stable" is a relative term by which most reefers mean don't let it do wild swings over several dKH regularly.---like going from 7 to 14. A swing between 8 to 10 isn't much of a swing in my opinion.
 

Bonsai reef

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For LPS/ softie you should not worry that much. You can stop the dosing and slowly bring it down to where it was.

Additionally, you may want to check on few things-

1. double check your refractometer calibration.
2. are you making your own RO/DI water or purchasing it from a fish store? Once my LFS gave me buffered water instead of plain RO/DI which was 15 dKh. If purchasing, measure the plain water for Alk.
3. if above two checks out then you may want to measure the new batch of water you make. Ideally it should be where your tank params are.
 
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NigelRichardson

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Thanks for all the inputs - as a relatively new reefer one of the things I've heard consistently is "It's all about water parameter stability" - which is great - but I've had a really hard time working out what "Stability" means

I've seen some You Tube reefers that auto test ALK every couple of hours and measure to the second decimal place, and I've seen a lot that suggest that if you're ALK is "Stable" between one-dkh-ish, you're doing ok.

Clearly there's (like many things) no "One" / "Correct" answer, but it is confusing... Hence why I was freaking out a little.

I'm making my own RODI water - confirmed as 0 TDS - so I don't think its that

I didn't test parameters of fresh batch of water prior to mixing (Confession - I never have / didn't even think of it) - Something I'll definitely do this weekend prior to next water change - thank you for the suggestion

I'll also make sure I mix around the bag of salt more in the future - again, something I never even considered!

Every day is a learning experience - which I guess what this hobby is all about !
 
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