ULNS and alk?

[authentic]

I run a ulns and have been recently advised to keep alk low 7.3-7.9 for best color,is there a known relationship between running high and low alk on a ulns system?presently running 8.5 no detectable phosphates (trying to raise with more feeding)

 

[jsker]

In general I have been told that I should be running the same alk, and I feed a lot. Here is a post that might help https://www.reef2reef.com/threads/ultra-low-nutrient-systems.160187/

 

[authentic]

will lower alk bring out colors??primarily sps tank,everything is looking good but im looking for better color.recently saw a BRS video indicating that the lighting is less of a factor than i thought,i have an ati 8 bulb 60 over my 140,at 16"above the water line.rather than lowering the light i thought of lowering Alk

 

[Randy Holmes-Farley Verified Community Expert]

No, alk itself does not impact coral color that I have ever seen demonstrated.

ULNS at any alk can result in more (or at least different) colors because the low nutrients reduce the zooxanthellae populations in the corals, and the zoox are golden brown. You often need to add supplemental food sources as the corals are starving or close to it in ULNS conditions.

Lower alkalinity with ULNS is needed in many cased to prevent burnt tips in SPS corals. One hypothesis of how that happens at higher alk is the skeleton grows faster than the tissue can keep up, resulting in thin and easily damaged tissue at the growing tips.

 

[authentic]

thanks randy thats whati was asking

 

[Randy Holmes-Farley Verified Community Expert]

You're welcome.

Happy Reefing.