Low Alkalinity New Tank Normal?



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Dec 9, 2020
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Hello all,

I recently set up a 300 XL back in early January. Cycled with Dr.Tins and used caribsea liferock and caribsea live sand. Cycle went great and within a month all was looking well. I have had two clowns in there for the last 3 weeks and are doing well.

All testing is looking good but the one that stands out is my alkalinity. First tested at 7.1 2 weeks ago and today is 6.5. I’ve been doing 10% water changes every week although probably not necessary I’m just getting into the routine.

Parameters as follows
25-26 degc
5-10 Nitrate
0 Nitrite
0 Ammonia
0.04 phosphate (started at 0.08 so has dropped a tad for some reason)

running filter sock and carbon and a skimmer, nothing else. Lights have been on for a month and amazingly had zero algae yet. I did dose vibrant twice (biweekly) hoping to reduce the uglies and so far so good.

It’s just the alkalinity that I expected to be higher. Don’t have a calcium or mag test kit but will get this weekend. Just want to make sure all is ready as I start getting corals over the next few weeks.

forgot to add, using RO water and Red Sea Coral Pro salt

Any insight would be great!
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Figuring out the hobby one coral at a time.
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Apr 24, 2018
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Way upstate NY
The process of cycling will deplete alkalinity. As the bacteria grow, they do consume some alkalinity.

Never actually tested ALK during a cycle(just remember reading that from Randy) so not sure if that consumption is abnormal.

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