Huge swings in Mag & Calcium on a DAILY basis. What's going on?

[Dylan Grech]

Hi guys,

This forum has been very helpful with all my beginner questions and was hoping some of you might shed some light on my ongoing problems with water chemistry. Tank has been up and running for about 2 months and the levels don't want to stabilize. LFS says the water still needs to buffer but I can't understand this concept to me it just seems that there is something really wrong and can't figure out what it is.

Rather than posting a huge thread on what I'm doing I've put a link to my aquaticlog profile which I use to record every single action I take on the tank.
http://www.aquaticlog.com/aquariums/dylangrech92/1
http://www.aquaticlog.com/aquariums/dylangrech92/1

 

[Dylan Grech]

Just some further info.

I'm suspecting it could be an issue with the test kit as the differences in values are fairly similar however I find this hard to believe as I test daily and clean the vials before and after every test so I find it hard to believe the test kit can be so wrong so many times.

Test kits:
- JBL MG/CA test kit
- JBL KH test kit

 

[lilchris_357]

I'm thinking Purple up is causing your swings in Cal and Mag. Are you testing at the same time each day? Stop dosing purple up for a few days and test at the same time each day and see if it stabilize.

 

[Dylan Grech]

I'm thinking Purple up is causing your swings in Cal and Mag. Are you testing at the same time each day? Stop dosing purple up for a few days and test at the same time each day and see if it stabilize.

I thought of that to be honest. I did skip a couple of days to see if it makes any difference but maybe 2 days is just too little. I'll stop for a week and see how it goes.

As per testing it's really dependant on the time I get back home from work. Sometimes it's 17:00 sometimes it's 19:00 and in the weekends I usually do it in the mornings

 

[Randy Holmes-Farley]

The results are testing error. It isn't possible for magnesium to jump up and down like that.

Same for calcium. While it can move a lot faster than magnesium, the changes are still not possible.

The LFS is giving bogus explanations. lol

 

[Randy Holmes-Farley]

It looks like you are topping off with tap water? That could be a problem, but not an explanation of your results.

 

[BrettMallette]

@Randy Holmes-Farley could it be a combination of different test times? Or is that more of a PH thing...

 

[Dylan Grech]

It looks like you are topping off with tap water? That could be a problem, but not an explanation of your results.

I do have fairly clean water at home due to a whole house softener + send filter system but I will have an RODI installed by next week so to be sure my top-off water is as clean as it gets.

@Randy Holmes-Farley could it be a combination of different test times? Or is that more of a PH thing...

I don't understand this concept of different test times. Could it make such a difference? And as per PH, my test probe just arrived so I'll start checking that twice a day to see how it's behaving.

 

[Mindi]

It is not so much a question of the tap water being "clean" as being free of certain chemicals like chlorine or chloramine which will kill your tank. Maybe I misread above but you cant use sanitised tap water without removing the chlorine or peroxide based sanitising agent. Agree above that you may have major testing errors. Stop testing daily...that way madness lies. Suspect a combination of test errors and some frequently introduced problem like odd topup water.
What test kits are you using..?.. and time of day doesn't matter except if it is before or after something else has been introduced. pH will typically drop a little overnight as any photosynthesis by corals or algae stops and CO2 is not consumed but absorbed into the water...making some carbonic acid and thus lowering pH a little.... but small and consistent changes.

 

[Dylan Grech]

A lot of useful info. Thanks guys!

 

[Dylan Grech]

It is not so much a question of the tap water being "clean" as being free of certain chemicals like chlorine or chloramine which will kill your tank. Maybe I misread above but you cant use sanitised tap water without removing the chlorine or peroxide based sanitising agent. Agree above that you may have major testing errors. Stop testing daily...that way madness lies. Suspect a combination of test errors and some frequently introduced problem like odd topup water.
What test kits are you using..?.. and time of day doesn't matter except if it is before or after something else has been introduced. pH will typically drop a little overnight as any photosynthesis by corals or algae stops and CO2 is not consumed but absorbed into the water...making some carbonic acid and thus lowering pH a little.... but small and consistent changes.

My system is fairly unique as how it works, I hate going in a lot of detail as it stirs up a lot of debate however just to clarify. The water softener uses salt + resin to remove limescale and any rock/metal from water. This ensures undetectable levels of KH throughout my house water supply. Before the softener there is also a sand filter this removes most particles from water (TDS) this brings the tap water TDS down from 1000+ to 80ish. After the filters the water is then trickled into a storage tank on the roof, due to low water consumption throughout the house the chlorine dissolve by the time I actually get to use the tank water (chlorine has also been undetectable in my water) and since in Malta we use a desalination plant to get water from the sea nitrites and nitrates are also in undetectable levels. This is what I mean by "clean tap-water". Now does this mean my tap water is perfect? By all means no! It still might have traces of silica, potassium, etc... and that is why I'm getting an RODI however the tap water is not dangerous to my aquarium just makes maintenance a bit harder due to the silica promoting a ton of algae in the refugium.

Sorry for long explanation but I hope this clears it quite a bit