Big difference in parameters when testing

[Kial]

Hey

So I use the red sea test kits and I just seem to get real random test results each time.

I usually test after my water changes (10% weekly)

For example, last week my mag was 1460 and this week it says somewhere between 1560-1600. Surly that can't be right with just a 10% water change?

Currently have:
2x hammers
1x goni
Few zoas and 1 morph

Any advice would be great

Thanks

 

[Sean Clark]

This could be just testing error and accuracy ranges stacked together. Try completing three test in a row and focus on the color change and not the syringe during those test. That will keep you from applying a conformation basis to your testing. See what you get.

 

[Kial]

This could be just testing error and accuracy ranges stacked together. Try completing three test in a row and focus on the color change and not the syringe during those test. That will keep you from applying a conformation basis to your testing. See what you get.

Just did a few more. Got 1400, then 1440

So it's different each time So who knows what the actual number is. However those numbers seem more realistic. The first test getting 1560 must of just been a testing error

 

[Sean Clark]

Just did a few more. Got 1400, then 1440

So it's different each time So who knows what the actual number is. However those numbers seem more realistic. The first test getting 1560 must of just been a testing error

Some of these test are pretty sensitive so process and procedures can play a large roll. Either way 1400 or 1560 is not really a problem. Some people use 1600+ Mag to fight back bryopsis. This can have negative effects on inverts at that level though. Keep an eye on it.

 

[Randy Holmes-Farley Verified Community Expert]

Hey

So I use the red sea test kits and I just seem to get real random test results each time.

I usually test after my water changes (10% weekly)

For example, last week my mag was 1460 and this week it says somewhere between 1560-1600. Surly that can't be right with just a 10% water change?

Currently have:
2x hammers
1x goni
Few zoas and 1 morph

Any advice would be great

Thanks

That is either test error or big swings in salinity.

Actual magnesium consumption is at most 2 ppm per day, and is not more than about 1/10th of the calcium consumption.

 

[gbroadbridge]

Just did a few more. Got 1400, then 1440

So it's different each time So who knows what the actual number is. However those numbers seem more realistic. The first test getting 1560 must of just been a testing error

There is no difference between 1400 and 1440.
It's within the measurement uncertainty of the test itself.

 

[Kial]

That is either test error or big swings in salinity.

Actual magnesium consumption is at most 2 ppm per day, and is not more than about 1/10th of the calcium consumption.

Yeah was more likely a testing error as salinity is fine

 

[Dan_P]

Hey

So I use the red sea test kits and I just seem to get real random test results each time.

I usually test after my water changes (10% weekly)

For example, last week my mag was 1460 and this week it says somewhere between 1560-1600. Surly that can't be right with just a 10% water change?

Currently have:
2x hammers
1x goni
Few zoas and 1 morph

Any advice would be great

Thanks

What are you measuring with Red Sea?

 

[Kial]

What are you measuring with Red Sea

Everything but phosphate which I have salifert

 

[Dan_P]

Everything but phosphate which I have salifert

I see the variance in magnesium testing has been clarified. Other test results are expected to bounce around some. I would guess that Red Sea tests might bounce 10% around the true value. Do your values swing that much, reading to reading?

 

[Kial]

I see the variance in magnesium testing has been clarified. Other test results are expected to bounce around some. I would guess that Red Sea tests might bounce 10% around the true value. Do your values swing that much, reading to reading?

I'm having a nightmare with my testing right now. Just did 3 test for alk and used 0.42ml of the titrant which comes to a dkh of 5.9. This can't be right with just a few corals and weekly changes.

Am I reading this correctly when it says 0.42ml titrant used?

Or do you go off the number that the plunger stops on within the pipette?

 

[gbroadbridge]

I'm having a nightmare with my testing right now. Just did 3 test for alk and used 0.42ml of the titrant which comes to a dkh of 5.9. This can't be right with just a few corals and weekly changes.

Am I reading this correctly when it says 0.42ml titrant used?

Or do you go off the number that the plunger stops on within the pipette?

 

[Kial]

OK so I'm definitely reading it correctly. Alk was 7.5 on Saturday. Today 5.9...

 

[Dennis Cartier]

Seems like a reasonable drop to me. 0.8 dKH/day is not unexpected if your hammers and goni are happy and growing.

It sounds like it is time to consider dosing.

 

[Randy Holmes-Farley Verified Community Expert]

It's certainly fine to boost to 7 dKH and see what happens.

Needing to dose is normal in a reef tank.

 

[MERKEY]

I know they are a bit expensive at first but the hannah checkers made our lives much easier.

While red sea and other color matching tests work well...they leave this kind of room for speculation and concern.

Hannah takes most of that questioning and concern out of the equation.

 

[Kial]

I've just ordered a hannah checker and some alk buffer so I can raise it.

Hopefully be here by the weekend so will test before and after my water change and then use the buffer to raise.

If by the weekend it's even lower, say around 5. What's the safest amount I can bring it up? Would it be too much to raise back to 7.5 which is what it usually is?

 

[homer1475]

Why not just use some baking soda, instead of waiting for buffer?

Probably have some in your fridge, or cupboard.

 

[Kial]

True. I'll have to watch some videos on that as not 100% sure on how much to use etc

 

[homer1475]

Reef Chemistry Calculator

Just choose Baking Soda as the additive.