SPS look great in my tank, but LPS dont do well

[PatientZero]

In almost 20 years of reefing this is the first time Ive had an SPS dominant tank. Didnt really plan it that way, just kept buying SPS frags. Since I switched from a 4 bulb to an 8 bulb T5, a lot of my LPS have slowly wasted away. My lights only run at 75% max, with most bulbs being blue+. I also dose kalk (and dont test alk). Being that Im an analytical chemist by day job, I have regular access to an ICP, and Ca and Mg are always spot on. What would make an acan or candy cane slowly melt, but make a A. austera grow like a weed?

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[FreshSaltH2o]

Water to clean?

[PatientZero]

That's possible I recently removed my GFO to see if that woukd help. Also have a octo 150ss on a 50 gallong tank, which only produces skimmate after I feed and then stops.

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[crustaceon]

I think your water is too clean for sure. I’ve had plenty of frogspawn and hammers that grew like weeds in 30ppm nitrates with awesome colors and suffered with anything under 10. It really comes down to your alk level and how it corresponds to available nutrients. I’m assuming with kalk, your dkh is probably around 7. This is fine in conjunction with low nutrients (some nitrates and Po4 needs to be there) to keep sps but will make life tough for lps and softies. I ran a mixed reef with acros, montis, torches, frogspawns, etc. for about five years at 9 dkh with that high level of nitrates. If it were me and at 7 dkh, I would allow my nitrates to rise up to around 10ppm, especially with that intensity of lighting. Probably the simplest fix here is having your skimmer on a timer and running it less each day to allow nutrient levels to rise in a controllable manner.

A second possibility is light acclimation. Many LPS thrive in lower light conditions like what a 4-bulb would provide. They can also thrive under far higher PAR levels if gradually acclimated and have the nutrition available to develop protective pigmentation.


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