Question on Chemistry Stability and Observed Parameters

[AKL1950]

System is still fairly new. My DT is going on 8 months since it cycled in. It’s a WaterBox 220.6 with the DT/sump containing about 180 gallons. (That’s total volume less displacement from live rock). I use an auto water change of 2.5 gallons a day using Reef Crystals. I feed twice daily and put out a 2” x 6” Nori clip. I feed a small amount of Reef Roids every 5 days. I dose 15 ml of Noephos per week. I dose 10 ml of Alk, 2ml of Ca and 5 ml of aminos per day. Stared introducing corals early September. I’m still gradually increasing the light in the tank. The PAR photo was two weeks ago, so the PARs are a little higher now. Around 310 at the top level.

My parameters are as follows:

Temp. 78.0-80.5
Salinity. 34.8
PH. 8.05-8.20
NO3. 11.0 +/- 2.0
PO4. 0.02-0.04
Alk. 8.2-8.4
Ca. 480
Mag. 1600

I‘ve done one ICP test last month and the parameters looked good and consistent with what I‘m showing.

My question is about the ranges of my Ca and Mag. They seem to be a bit higher than the “ideal” range, but all the parameters are extremely stable and are not moving up or down. I do have quite a few Acro frags and they are all showing goI’d growth. Is it this is just where my system is stabilizing at, or is it still too early to tell? Should I expect to see Ca and Mag start decreasing as the corals start growing bigger? Right now they are just rapidly encrusting their posts and don’t show much vertical growth.

I’m wanting to go with the if it ain’t broke, don’t fix it, but wanted to see if there were some things I should consider now that things are looking very stable.

 

[TokenReefer]

Are you dosing anything for Mg?

Edit: Also, what product are you dosing exactly for alk and ca?

 

[AKL1950]

Are you dosing anything for Mg?

Edit: Also, what product are you dosing exactly for alk and ca?

Brightwell parts A and B. I’ve got the Mag dosing set up to go, but the Mag stays around 1580-1600 with the daily water change so far, so I haven’t started dosing Mag.

 

[TokenReefer]

Even with daily water changes something doesn't add up. At 1.026 sg a fresh batch of IO RC should be at 1320 magnesium. So just numbers wise it doesn't make sense. The corals should be consuming it, dropping that number further.

When was the last time you calibrated your refractometer/probe to ensure salinity is correct? (higher salinity may account for the higher level)

Assuming sg is correct. What are you testing Mg with? Could it be drastically off?

This is just basic stuff but perhaps a local expert can chime in

 

[AKL1950]

Even with daily water changes something doesn't add up. At 1.026 sg a fresh batch of IO RC should be at 1320 magnesium. So just numbers wise it doesn't make sense. The corals should be consuming it, dropping that number further.

When was the last time you calibrated your refractometer/probe to ensure salinity is correct? (higher salinity may account for the higher level)

Assuming sg is correct. What are you testing Mg with? Could it be drastically off?

This is just basic stuff but perhaps a local expert can chime in

I use Apex trident and Salifert for backup on Ca and Mag. They are always very close to each other.

For Alk I use Trident, Salifert and Hanna. The range is always around 0.5 with Trident low, Salifert middle and Hanna high.

For Salinity I use Trident, Hanna and a refractometer. They all show the same.

The trident/Apex probes get calibrated every two months. I also did a ICP last month and it showed my numbers were correct. It had Salinity 35.0, Alk 8.2, Ca 460 and Mag at 1660.

 

[AKL1950]

Even with daily water changes something doesn't add up. At 1.026 sg a fresh batch of IO RC should be at 1320 magnesium. So just numbers wise it doesn't make sense. The corals should be consuming it, dropping that number further.

When was the last time you calibrated your refractometer/probe to ensure salinity is correct? (higher salinity may account for the higher level)

Assuming sg is correct. What are you testing Mg with? Could it be drastically off?

This is just basic stuff but perhaps a local expert can chime in

Correction on the ICP

my Alk was running lower and I increased the dosing to get it up to the 8.2 level

 

[TokenReefer]

my Alk was running lower and I increased the dosing to get it up to the 8.2 level

What are you using? I use ESV bionic for example and there is Mg in the second part (although only a small amount); just trying to figure out how mg could go so much higher (or higher at all) than the starting value of the salt mix with admittedly no Mg being added on purpose/from another source. I'm leaning toward testing error but you've cross-checked between a few different so I'm stumped at this point

 

[AKL1950]

What are you using? I use ESV bionic for example and there is Mg in the second part (although only a small amount); just trying to figure out how mg could go so much higher (or higher at all) than the starting value of the salt mix with admittedly no Mg being added on purpose/from another source. I'm leaning toward testing error but you've cross-checked between a few different so I'm stumped at this point

And now you see why I posted this thread. I’m not smart enough on chemistry, but I can see something doesn’t seem right.

Two things I have thought of.

First, when I set up my Apex dosers, I mistakenly put the Mag in the Alk bucket and the Alk in the Mag bucket. However, I’m dosing Alk and the values are rising as expected. if the Alk was in the Mag bucked, which I’m not dosing, I would think it would be dropping pretty quickly, but it’s not doing that.

Second is the only other things I’m putting in the tank are food and Sunnyx’s marine snow formula. Wasn’t sure if what I feed has any thing to do with major elements, but I feed a lot. About 8 different frozen foods plus flakes and pellets. If you can imagine a big tic on a cows ear, that’s what they look like. Pretty fat. The list:

LRS Fish Frenzy
WWC Reef Mix
Reef Plankton
Marine Quisine
Krill
Cyclops
Spirulina Brine Shrimp
Frozen Fish Eggs
Ocean Nutrition Spirulina Flakes
Ocean Nutrition Formula One Flakes
New Life Spectrum UltraRed Pellets
New Life Spectrum AlgeaMax Pellets.

 

[Randy Holmes-Farley Verified Community Expert]

The salinity above 35 ppt acounts for a boost of about 24 ppm magnesium. Not sure why (or if) the magnesium is really that high.

Do your home tests read that high in new salt water?

 

[AKL1950]

The salinity above 35 ppt acounts for a boost of about 24 ppm magnesium. Not sure why (or if) the magnesium is really that high.

Do your home tests read that high in new salt water?

I just twisted the Mag in my saltwater reservoir Using Salifert. I came out at 1510 ish.

 

[AKL1950]

The salinity above 35 ppt acounts for a boost of about 24 ppm magnesium. Not sure why (or if) the magnesium is really that high.

Do your home tests read that high in new salt water?

Salinity in the reservoir is 34.8. When I mix salt, I do about 50 gallons at a time. I use a 40 gallon bag and then use a calculator to see how much more salt I need and get that out of a 200 gallon salt bucket. I suppose there could be a concentration of Mag when I get it out of the bucket, but my DT Mag has never been below 1527 and usually sits between 1570 and 1600. That’s with Trident and Salifert.