Kali vs baking soda

[Subillbo]

Hi peeps.....
I have the nano evo 13.5 and do a 3 gal water change every friday, water parameters are great, but find that my Ph drops below 8 to around 7.4 later in the week... I started using baking soda in my ATO and has helped a lot. But my calcium(which I just stared checking) is low at around 250.... I was wondering if I should start using kalkwasser instead of using baking soda and adding calcium. My corals are doing fine, but thanking they could be doing better, so I want to add calcium..... so kalk or 2 part baking soda and calcium. As always thanks!

 

[dkeller_nc]

Yes, it's generally necessary to supplement calcium and alkalinity in a reef tank with actively growing LPS and/or SPS corals over an above what water changes can keep up with. An alternative is a nearly 100% water change as is typically practiced with "reef bowls" (<1 gallon reefs run with an air stone and an external source of heat), but to do this successfully requires very strict attention be paid to matching water chemistry, salinity and temperature exactly between the tank's current conditions and the change water.

So most aquarists choose to use supplementation with chemical solutions, in this case so-called "2 part" with calcium chloride and sodium carbonate/bicarbonate solutions. This article will get you started, and you can buy convenient pre-measured components from Bulk Reef Supply.

By the way, pH swings in a reef tank are expected and generally aren't a problem; maintaining alkalinity is considerably more important. Keep in mind that if you're measuring pH with a test kit, they are not usually very accurate in saltwater. In any event, having low alkalinity will cause a larger swing in pH than would normally be the case, and I'd suggest getting the calcium and alkalinity concentrations stable before being too concerned with pH values.

 

[nereefpat]

Check your alk

 

[Subillbo]

Check your alk

Ok I finally got an alk test kit... got the salifert kh/alkalinity kit. I tested a few times and i am getting around 13..... that seems rly high. is this level bad? Should I lower it? I have all sps corals, bunch of zoas, pulsing xenia, candy, gsp and hammer..... ive read a bunch of different opinions online so looking for some clarity.... as always thanks!

 

[WVH]

Magnesium is also critical in maintaining a balance with hardness and calcium. If the mag is low its very hard to get your calcium up to correct levels . Here is a quote from Advanced Aquarist on the subject
Finally, if you are adding large amount of calcium and alkalinity supplements, but just cannot maintain the desired values, you might want to measure the magnesium level in the water. Magnesium plays an important role in preventing the abiotic precipitation of calcium carbonate1, and if it is substantially depleted, you may be experiencing excessive amounts of calcium and alkalinity loss to this route. Magnesium gets the blame far more frequently, in my opinion, than it is likely responsible, but since it is easy to check with a test kit and easy to supplement if necessary, there's no reason to not see if it is a problem. I'd advise aiming for a natural seawater level of about 1300 ppm.

 

[dkeller_nc]

Ok I finally got an alk test kit... got the salifert kh/alkalinity kit. I tested a few times and i am getting around 13..... that seems rly high. is this level bad? Should I lower it? I have all sps corals, bunch of zoas, pulsing xenia, candy, gsp and hammer..... ive read a bunch of different opinions online so looking for some clarity.... as always thanks!

First things first, make sure that you're not over-titrating the Salifert test kit. The final color should be lavender, not orange. But yes, an alkalinity of 13 would be considered somewhat high for a reef tank. That said, stability is more important than the exact number, so don't rapidly change it with water changes trying to get it down to 8-10 dKH. Instead, stop dosing baking soda and let it naturally fall over a few days.

Again, if you're assessing pH with a test kit, stop testing. The kits just aren't accurate, and pH isn't all that important in a reef tank anyway. If you're assessing pH with a correctly calibrated pH meter, then the swings you've noted may be due to a build up of carbon dioxide in the water. That can be caused by insufficient aeration/flow, and can also be caused by build-up of CO2 in the air in your house. In any event, don't dose sodium bicarbonate/sodium carbonate in an effort to achieve a specific pH. It can't be done, and you will potentially get wild swings in alkalinity that will compromise the health of your corals.

Finally, and in general, never dose anything that you can't test for, at least as far as inorganic salts like calcium chloride, alkalinity reagents like sodium bicarbonate/carbonate, or magnesium supplements are concerned. Instead, buy your test kits and get familiar with them before you contemplate adding solutions to the tank.

 

[CAPT_Dave]

Baking soda adds Alk but not Ca. It also lowers pH. I've never heard of it being dosed in top off. Anhydrous baking soda (baked to remove all water) raises it. But you need to dose both Alk and Ca together (but separately). It's known as 2 part and can keep up with a pretty high demand even in large tanks.

For yours, I would start with Kalkwasser. Kalk is one of the few ways to dose both in one product and you can do it in top off. That's all I use in my mixed reef 120.

But FIRST you need to get Ca and Alk in balance. Slowly. Slowly. As recommended previously, stop dosing and let Alk fall naturally while simultaneously dosing Ca to slowly bring that into range. Slowly. Once you get in range do a couple water changes, then start dosing Kalk in your top off. The most you can dissolve in water is 2 tsp per gallon. I would start with 1 and test Alk daily for about a week and see how it goes. If Alk falls, you can add some more powder to your top off water. If it goes up dilute with more RO/DI until you get stable. Read up on this-lots of good posts on RC.

This will also raise pH so be careful. You need to have a means of shutting off top off if pH spikes too high if your ATO fails on. That actually happened to me last week. My Apex shut it down and saved my tank...and my living room.

BRS has a great calculator on their website for determining how much of various products to use. I think it was created by Randy Holmes Farley, which means trust it.

Did I say go slow?

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[CAPT_Dave]

Oh, and read the sticky post titled "Dirt Simple Chemistry..." on this forum.

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[Subillbo]

Thanks for the info peeps!