Big swings of parameters after water change

[krayzie]

Hi guys!


I have a waterbox 20 (~75.5 litres) that is stocked with LPS (torch/hammer/frogspawns) and i have started to auto dose alk cal mg and it has all been going well and i have been matching the daily up takes of these elements


Then comes Fridays when i normally do water changes. I have been doing 25Litres (~6.6 gal) which i think its about 34% water change


Here lies the problem once the water change is complete my parameters fall dramatically


I tried to keep KH at 8 after WC it falls to about 0.5dkh


Cal 450 before WC and after 420ppm


MG 1300 before WC and after 1200ppm

I use NSW for the WC and the parameters for it are
DKH:7
CAL: 430
MG:1200


This is just last water changes but some of the swings have been bigger


What's the best thing to do? I feel like smaller water changes per week would be better? I know everyone says 10% is that what i should be doing?

Or am i worrying about nothing as its in spec for NSW?

Thank you

 

[braaap]

Personally I wouldn’t worry about it. See how your coral reacts. A .5 dkh drop isn’t a huge deal. But I wouldn’t want more than that.

You can always dose your new water to bring it closer to the tank.

 

[GlassMunky]

Just test the new water and adjust it prior to the water change and then you could do a giant change and nothing will shift


But yes, NSW is low in numbers compared to what we keep reef tanks at, that’s normal.

 

[Randy Holmes-Farley]

Some of the results are test error. Magnesium dropping 100 ppm, for example. I’d just stop measuring it.

 

[Lavey29]

So just do a 20% water change instead of 34%.

 

[MERKEY]

Those differences arent bad at all BUT If it really bothers you....you can try to slowly change salt to one that mixes higher and closer to your target parameters.

 

[GlassMunky]

Those differences arent bad at all BUT If it really bothers you....you can try to slowly change salt to one that mixes higher and closer to your target parameters.

NSW
NATURAL SEA WATER.
No salt mixing at all

 

[EricR]

Or am i worrying about nothing as its in spec for NSW?

I feel like yes -- overly worried about nothing.
If you're collecting your own water (I think) and doing large, frequent water changes, seems like you'd be better off seeing how your tank likes the natural parameters.

Other option, as previously mentioned, is dose up what you care about in your NSW prior to water change.

 

[14 foot reef]

Maybe I read this wrong, but if you are doing NSW changes, and your tank has higher perimeters than your water change water( NSW ) then of course a 35% water change is going to lower your perimeters in your tank somewhat.
It's a natural dilution process.

 

[Randy Holmes-Farley]

Obviously the water change did not cause the calcium and magnesium observations, making them likely test error.