Minerals out of whack after cycle and water change

drjreber · Aug 31, 2023

Hello. I just finished cycling my Biocube 32. I used bottle bacteria (two brands) and fed it one round of ammonium chloride. Cycle went pretty much as expected over the course of 17 days -- ammonia and Nitrite were at 0 (with API) and at 0 and 0.2 using Salifert, respectively. Nitrate was over 100, according to Salifert test. Decided that meant I should do a big water change, so removed about 90% of the water and replaced it with freshly mixed Instant Ocean Reef Crystals. Adjusted salinity to 1.025 at 80 degrees and added it to the tank. Today, I tested all of the other parameters. All tests Salifert unless otherwise stated.
Sal and temp same as yesterday (1.025 and 80 degrees)
pH 8.2
Phos 0.01
Alk 10.1
Nitrate 25
Nitrite 0.25
Ammonia 0
Mg 30
Ca 100

I am puzzled by the Nitrite and Nitrate levels. Where did an increase in Nitrite come from, and is 25 ppm too high for nitrates until my next water change (assuming that doesn't make things worse).

I am even more frustrated by the Mg and Ca levels. I am a scientist by training, so I know I did the titrations for Ca and Mg correctly. I retested both many times, and even had a senior biology research major run the Ca test to be certain I wasn't just having a brain burp. I have no idea why the levels are so low or how to fix them - I have fish and crabs coming tomorrow (fish going into copper quarantine, hermit crabs will be gently scrubbed with DI water and released into this tank).

Anyone have any ideas of what is wrong (tests or reef mix) and how to fix it rather quickly?

Thanks!

brandon429 · Aug 31, 2023

Truly you need a second confirming test reading for the calcium and alk. A different brand ran and compared, not just that kit reran to state accuracy

That reading is suspect because it doesn't mix to that out of the bag it's unlikely compared to the degree of misreads on file between two different test kit types. It's more likely a kit quality error than io being-300 off in calcium for recently purchased and used io brand salt

KrisReef · Aug 31, 2023

Assuming that you mixed with RODI water and not tap?

I agree something is wrong with Mg and Ca results, hopefully the test kits are off.

Randy Holmes-Farley · Aug 31, 2023

Are you sure you are not reading the kits backwards?

drjreber · Sep 2, 2023

Haha-Yes, reading kits correctly. Waiting for new kits and will retest. I live in a very rural area and Instant Ocean is pretty much the only saltwater supplies my LFS sells.

Randy Holmes-Farley · Sep 2, 2023

drjreber said:
Haha-Yes, reading kits correctly. Waiting for new kits and will retest. I live in a very rural area and Instant Ocean is pretty much the only saltwater supplies my LFS sells.

Ok, because it is not uncommon for folks getting very low values to read the volume left in the syringe instead of the volume added. This misunderstanding seems confined to the Salifert kits.