New Tank Dosing Questions

[the meadows]

I am about 8 weeks into a new 120 gallon reef tank. I only have live rock and a few small extra mushrooms that were on some of the rock from my current 46 gallon reef tank. I have done one small water change and getting ready to do another today. I have noticed that Ca & Mg are a little low, which tells me to do water changes. However, I am set up to dose both Ca & Mg. At what point do I need to start dosing? I can tell on my small tank when to dose compaired to my scheduled water changes to help my hardness levels. This new tank, with only live rock, has acted completely different from my 46 gal.
Also, at what point do I need to start running my skimmer?
Thanks for the help! I'm a newbie to RC.

 

[Randy Holmes-Farley]

With that tank, if the calcium and magnesium are low it is because the starting salt mix is low, not because the tank used them.

If you do not need to dose alkalinity, then calcium and magnesium are not being noticeably used.

So gauge whether you need any dosing at all on the alkalinity, and if the calcium and magnesium are low in the salt mix, consider adjusting that somehow.

What mix and what salinity?

 

[the meadows]

Salinity is 1.025. I use reef crystals. That is what I have available at the LFS.
Alk is 10.5 dKH.
I am glad you replied. I have read several of your posts. I work at an RO water treatment facility which I have food grade soda ash at my disposal. Can you give me some background on dosing SA for Alkalinity in my reef tank?

 

[Randy Holmes-Farley]

Soda ash (sodium carbonate) is a good supplement. It is fine as a stand alone alk supplement, and as part of a DIY two part. I describe how it is used (and made from baking soda) in these articles:

Solving Calcium and Alkalinity Problems
http://www.advancedaquarist.com/2002/11/chemistry

The “How To” Guide to Reef Aquarium Chemistry for Beginners, Part 2: What Chemicals Must be Supplemented
http://reefkeeping.com/issues/2007-04/rhf/index.php

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System
http://reefkeeping.com/issues/2006-02/rhf/index.php

 

[the meadows]

Thanks for the info.
To my second question. I have no mechanical filtering except for the skimmer. I used filter cloth for a couple of weeks to remove debris from the sand. I have rubble in the sump and a refugium(my first). So, with no fish of corals, at what point do I need to start skimming?

 

[Randy Holmes-Farley]

Well, not yet anyway.

Do you add and foods to the tank?

 

[the meadows]

I used a shrimp to help the cycle process. I add a little brine shrimp a couple times a week. VERY LITTLE!

 

[Randy Holmes-Farley]

That sounds like a fine plan.

 

[trinidiver]

What exactly are your Cal and Mag readings in #'s

 

[the meadows]

Ca 370
Mg 1090
Alk 10.5 dKH

 

[Reefer54]

they could be a little higher and alk a bit lower imo. but they arent far off. if you do regular water changes they may even out. does the reeff crystals bucket state what the water elements should read at when the water is mixed to say 1.025...thats where id start. if the stated pareameters differ, then id check your tests or testing proceddure.

good luck. aint it fun

 

[the meadows]

They are not far off but not in the range that I would like them to be. They have been low (ca & mg)since the first few weeks. Alk has been high also. I had a friend test my water with different brand kits with the exact same outcome. I did a 10 gal water change yesterday. Numbers came up to ca 410 & mg 1230. Going to do a couple of 20 gal water changes over the next week. I think that will put me back on track.

And yes, I LOVE IT!!!

 

[Randy Holmes-Farley]

The RC parameters for calcium and magnesium will be a higher at sg = 1.025, and even higher again if you boosted to 35 ppt (1.0264 or so).

 

[the meadows]

So, is 1.024 sg optimal?

 

[Randy Holmes-Farley]

I prefer to match the higher average levels naturally found in most reefs, at 35 ppt (= 1.0264).

That said, I'd be hard pressed to prove whether 1.024 or 1.026 or 1.028 was better.

 

[the meadows]

Thanks again! I appreciate the help & experience.