Will low alkalinity hurt corals?

ThePurple12 · Oct 13, 2020

I looked into pickling lime and it sounds like a good idea, but Amazon is out of stock currently.

Do you know how much pickling lime to add per gallon?

Privateye · Oct 13, 2020

Honestly, I wouldn't add hydroxide to fix a carbonate problem. It could help indirectly but it's really not going to increase your alkalinity.

Go with the bicarb, or if you want to go stronger I use soda ash: https://www.walmart.com/grocery/ip/...rgent-Booster-Household-Cleaner-55oz/19407690

I mix my own stock solution (I just do it to saturation, but you can add whatever works for you) and dose it with this dosing pump: https://www.bulkreefsupply.com/x1-bluetooth-micropump-kamoer.html

As someone who battles low calcium, alkalinity, and magnesium often, I highly recommend you raise it. It's not far away from a danger zone, so an increase could make things safer for your coral. I've neglected my chemistry many times over the years, only to wake up and find a coral is 3/4 bleached. It happens fast if you drift too low, and as your corals grow in size they will consume alkalinity faster.

ThePurple12 · Oct 13, 2020

That's good to know. I'll keep using baking soda then, and just increase the dosing probably with an auto feeder.

TexasTodd · Oct 14, 2020

All you need is Kalkwasser. Work your way up by slowly increasing the mixture, testing your alk. Start with maybe half Tsp per gallon and watch. Are you doing water changes? How often and what percentage?

GlassMunky · Oct 14, 2020

I’ve had my coral QT tank running at an ALK of 6 or less for several months now and all sps are fine and growing. Even have a 20” clam in there doing just fine.

ThePurple12 · Oct 14, 2020

OK, so there’s a lot of different experiences/opinions.

Texas Todd, I was doing 15% monthly, but I’m going to increase that. I don’t think water changes are the whole issue, because back when I had a 75g and was doing 20% a week my alk was still low with just a few SPS.

Privateye · Oct 14, 2020

Kalkwasser and pickling lime are both calcium hydroxide. They increase your pH but not your KH. KH is carbonate hardness, and it represents the majority of your alkalinity in a marine environment. Dosing carbonates and bicarbonates will restore KH, and carbonates are used to build coral skeletons.

Fishfinder · Oct 14, 2020

Privateye said:
Kalkwasser and pickling lime are both calcium hydroxide. They increase your pH but not your KH. KH is carbonate hardness, and it represents the majority of your alkalinity in a marine environment. Dosing carbonates and bicarbonates will restore KH, and carbonates are used to build coral skeletons.

that is incorrect

Fishfinder · Oct 14, 2020

@ThePurple12
You seem to have a low demand tank. If you add kalk to your top off it will increase your alk. Depending on your evaporation, most likely very slowly.

ThePurple12 · Oct 14, 2020

The thing is, every time I dose it comes back down to 5-6 in 2 or 3 days. I have no idea why.

stephj03 · Oct 14, 2020

@ Privateye & ThePurple12

I would strongly reccomend you skim this article by the man, the myth the legend himself.

http://www.reefkeeping.com/issues/2005-01/rhf/#16

Snipets about Kalk progression in saltwater as an alk supplement

Kalk dissolves in water

CaO + H2O >>>> Ca(OH)2

Hydroxide component of kalk interacts with CO2 in the water to form useable carbonate for calcifying corals

OH- + CO2 >>>> HCO3-
OH- + HCO3- >>>> CO3-- + H2O

stephj03 · Oct 14, 2020

There's a common rule regarding checks written by Randy Holmes-Farley about general tank chemistry.....

You take them straight to the bank vs weighing equally with other input

If you dose and it still goes down it is:

1. Either being used by your SPS/LPS to lay down new skeleton

Or

2. Precipitating out of solution as calcified deposits on your pumps and plumbing

Or

3. Being used by coralline algae

Whichever of these 3 you see the most of is the likely sink.

Keep in mind, it's not uncommon for a moderately stocked LPS/SPS tank to drop 1dkh in 24hrs if not actively supplemented.

SPS is not a passive income game like softies. Be prepared to continually invest money, time and Ca/Alk into them.

ThePurple12 · Oct 14, 2020

It must be coralline for me, it grows all over the glass. Thanks for the article, I'll read it now

stephj03 · Oct 14, 2020

If you're having to scrape coralline often, that would def explain a significant alk demand amidst a lack of precipitation and significant SPS growth.

I use to love having as much coralline as possible but anymore anything a few patches of it represents Ca/Alk dosing that could have gone into a high end acro instead.

stephj03 · Oct 14, 2020

GlassMunky said:
I’ve had my coral QT tank running at an ALK of 6 or less for several months now and all sps are fine and growing. Even have a 20” clam in there doing just fine.

I know it's a massive derail but this is by far THE POST of this thread and did not receive nearly the "likes" it deserves.

20" clam and a bunch of growing SPS in a QT rig!!!!

That's beyond baller.

TexasTodd · Oct 14, 2020

Yes, you should be dosing as often as your top off and hopefully small amounts at a time throughout a 24 hour period. Honestly kalk and water change is probably all you need with what you have going. Just test a lot at first and start with a low amount in your ATO like 1/2 tsp per gallon.

ApoIsland · Oct 14, 2020

ThePurple12 said:
My alkalinity is perpetually low, at around 5.5. Without daily or several times a week dosing, it will stay that low. Dosing daily isn't ideal for multiple reasons, including messing with the stability. Will my SPS be OK if I just leave it that low?

If your corals are doing fine I wouldn't worry about it at all. Maybe up your monthly wc% to 30 or 45% if you are really concerned.

10 years ago, the last time I was into testing, my alk was always so low. I have a tank packed with lps and low end easy sps similar to what it looks like you have. I do monthly 50% water changes with no dosing. The only time I had a problem was when I used Reef Crystals and doing about a 75% water change once. I think because of the elevated levels of that salt and large water change % I shocked everything a bit. Never any issues using Instant Ocean regular or Coralife (basically the two cheapest I can find).