High ALK Issues

[Sapelo]

My reefing other half has determined that ALK needs to run higher than I believe that it should. To his credit, he's holding it rock solid steady via dosing pumps. We're just getting into SPS and I'm wondering if anyone can comment on the down side of holding ALK at 11kh.
Thanks.

 

[jason2459]

Here's a good read for the common parameters we should be looking for
http://www.reefkeeping.com/issues/2004-05/rhf/index.php

11dkh Alk is on the high end of the scale but is just fine. However, if getting into SPS heavy tanks many will drive their nutrients like Nitrates and Phosphates very very low. Many posts have stated issues with these very low nutrient systems and higher alk values. So, if you get into keeping undetectable Nitrates via test kits that can track under 1ppm of Nitrates and PO4 under 0.03 then I would lower the Alk values closer to the beginning of the range of around 7-8dkh.

 

[heathlindner25]

I don't know why he would want to keep it at 11 for any system?

 

[jason2459]

I personally target around 9-10 but I usually don't have to do anything to hit that with ~1% daily automatic water changes and limewater in my ATO.

 

[Sapelo]

Thank you very much for the article and your thoughts, they are much appreciated.

 

[Reefaholic1978]

Agree with what was said above, once you attain low levels of nitrate and phosphate corals will start to use up calcium to build skeleton and with such a high dkh will get burnt tips so 7.5 to 8 us ideal. You will still get good growth of tissue and coral skeleton. That's just from my experience through trial and error.

 

[Sk8r]

I have always had excellent lps growth at 8.3, cal 420, mg 1300, fwiw.

 

[cincyjim]

How do you lower Alk? For the most part, I've seen only water changes lower Alk. Are there other ways to lower it?

 

[jason2459]

How do you lower Alk? For the most part, I've seen only water changes lower Alk. Are there other ways to lower it?

Easiest way to do it is do absolutely nothing. Water changes could raise the Alk levels if your water change water has higher alk witch some brands have fairly high alk values. Like Reef Crystals and many other "reef" specific salt brands.

By not dosing anything like buffers, 2 part, kalk, etc the Alk will naturally go lower as things in your tank consume it as part of their calcification process like stony corals and coralline algae.


Otherwise you could use muriatic acid in your water change water to low it's alk value and slowly lower your tanks alk value. BE VERY CAREFULL with muratic acid. Keep it away from children and pets. Keep it off your skin, eyes, and lungs.

There are other things like GFO that will lower Alk as well but not very significantly.

You want to stay away from drastic Alk swings as stoney corals will not be happy with you and could be damaged or even become a complete loss.

Another good read
http://www.advancedaquarist.com/2002/2/chemistry
http://www.reefkeeping.com/issues/2002-04/rhf/feature/index.php
http://www.advancedaquarist.com/2002/11/chemistry