Chemistry fluctuation..

[Playdope]

I have been doing daily testing, and I've noticed some fluctuation in my water parameters. I am wondering if this is normal, or if I need to change/configure something better.

Day 1:

Salinity = 53.4
pH (ppm) = 8.12

Day 2:

Salinity = 52.4
pH (ppm) = 8.18

Day 3:

Salinity = 51.4
pH (ppm) = 8.15

Day 4:

Salinity = 52.1
pH (ppm) = 8.27

Should I keep watching it a few more days? I'm a little unsure as to why the salinity dropped like that. I should add that I started testing the day after I did a water change (checked the salinity of water before adding and was 53.1). I also thought some of it may have to do with the fact that the skimmer may be pulling water out of the tank, because I made the skimmer skim a little less hard on Day 3, so I thought that may be the reason the salinity bumped up again.

As for the pH, is this kind of fluctuation normal. I've been noticing this kind of fluctuation for some time now. I am using a Hanna handheld pH meter during the day - i haven't tested at night. I am waiting for a new probe for my pinpoint monitor to arrive to double check my values.

How much are aquarium parameters allowed to fluctuate in a 24 hr. period?

Many thanks!

 

[Fatal Morgana]

What did you use to test the salinity in your tank?

As for the pH, the first 3 days only show a few tenth of a swing. That's pretty much is the limit of most hobby pH meter, and I would just see them as identical value. The 4th day is slightly different, but again, it is just a handheld meter, and I bet if you did the measurement a few more time, it will show you "identical" value. Don't sweat too much there

As for the salinity, I need to know what you use to find the number. Swingarm hydrometer will surely give you wild values above, and again, don't sweat too much.

As for your explaination about dropping salinity due to the skimmer, I doubt it is the case for a 100 gal tank. Knowing that skimmate (junks in skimmer cup) has a lower salinity than tank water, it actually will increase salinity if you have an otherwise perfectly closed system. Furthermore, evaporation also will increase the tank's salinity over time. Both facts seem to be contradictory to what you measure, and again, I won't comment until you tell me what you sue to get the numbers.

This, of course, assume you did not have a topoff that add freshwater to the tank to replace the evap. water.

 

[Playdope]

I am using a Pinpoint Salinity Monitor.

So, that pH is normal!? 8.15==>8.27 in one day. Should a pinpoint pH monitor be more accurate than the hanna handheld?

I also a LiterMeter II that is topping off evaporated water.

Thanks

 

[ChrisRD]

The pH numbers look fine and swinging from 8.15 to 8.27 in a single day is normal IMO/IME. I'm sure you realize those monitors require periodic calibration, so if you suspect the numbers are off you can always get some calibration solution and make sure it's dialed-in.

The salinity numbers look odd. What unit of measure is the unit supposed to be displaying?

 

[Fatal Morgana]

The unit looks like it is milliSiemens (mS). NSW has a salinity/conductivity of around 53 mS, depends on temperature, pressure, etc..

 

[ChrisRD]

Ah, right... ...forgot about conductivity values...

 

[Playdope]

Just took another reading today...

Salinity - 52.2
pH - 8.27

 

[ChaoticReefer]

A normal pH daily cycle can swing between 7.9 and 8.3. Also, I have seen outstanding tanks with pH high as 8.4 and 8.5. So I won't get too worried, you are within the range. Also you might be testing at different times of the day. If you test pH right before the lights come on and 8 hours into the lighting period you will certainly see a pH difference.