Should I dose more than just Alk, Ca, Mg?

[Salty Pickle]

I have a 25 lagoon (approx. 21 gal. actual water vol.) that is packed with SPS, 28 to be exact. They all started out as 1/2 to 3/4 inch frags which contributed to my shortsightedness, but the bug bit me. As the corals have continued to grow over the past 7 months the colors have looked spectacular. Recently I have begun to lose colors on virtually every coral, good news is there is no tissue damage on any of the corals, polyp extension is great, growth is still steady.

 

My parameter have been stable for the entire time:

Ca = 400-440 Hanna

Alk = 8.4-8.7 Hanna

Salinity = 1.025-1.026

Temp = 78.5-79.0 Apex controlled

pH = 8.0-8.3 Apex probe

Mg = 1340-1380 Salifert

NH3, NO3, NO2, PO4 = 0 Salifert

 

My lighting schedule has not changed and I change 1 t5 bulb every 2-3 months so i don't have any significant light diminishment over time. My flow has not changed at all and the MP10 is working as it should. I perform weekly water changes with Kent salt mix. I am currently dosing 18 ml a day to maintain ALK and Ca using 2 part using Bightwells, I also dose Mg.

 

Sorry for the long intro but I figured that at some point in the discussion I would be asked all these questions. I am trying to figure out why everything is beginning to brown out.

 

Is it possible that the corals are consuming all the other elements in the water to the point that weekly water changes are no longer sufficient in replacing them?

 

If yes, what should I start dosing to bring the colors back?

 

I have a Kamoer 3 channel doser along with the 4 channel doser which is a total of 7 pumps so adding things to the dosing regiment is not an issue. I just don't know if its necessary and if so what?

 

 

There is also the possibility I am completely off base. Before I digress any further, I will end here.

[ManGups]

Weekly water changes is enough to replace trace elements such as iodine, strontium etc. also they are NOT recommend to be dosed. Please read Randy Holmes article on reef parameters.

You really only need to dose Alk and Ca...
The 5 ~7 dosers are used when you follow methods like the aqua forest guide

[HuyHa114]

Sounds to me that the corals are either bleaching by too much light or starving because of the low nutrients. You can either raise your lights or feed more to your fishes. You can also dose amino acids if you have low nutrients to help with coloration.