Why is my tank Ca level almost so low?

[Felix Wong]

Hi Reef Club Members,

Need your help on this calcium issue.

I have a 2 ft tank with some damsels & corals like sun coral, jewel coral, frogspawn, hammerheads, octopus coral & zooanthids + a starfish.

After changing 30% water, the Ca level would drop from 460 mg to 210 mg as measured using X-Glare Ca test kit. Then I would four 5ml spoonful of Seachem Ca Reef Advantage powder (dissolved in water) over the course of 2 days to bring back the Ca to at least 420 mg. Also added two 5 mL spoonful of carbonate.

The puzzling thing is 2 days later the Ca level has dropped to 150 mg. Then I added four 5mL spoonful of Ca again over the course of 2 days but 1 week later, the Ca level is still at 180mg.

1. Is Ca absorbed at such a high rate just over a few days?

2. What is the normal Ca dosing like for a 2 ft tank? Is 5 ml spoonful twice a week good enough as instructed on the bottle of the Seachem product?

3. Or is it because X-Glare Ca test kit does not provide accurate end point reading?

4. What Ca test kit would give the clearest end point and accurate reading?

Thanks and I hope someone could enlighten me on this issue.

Felix

[prec]

Try Salifert Testkits. Its pretty much used by most reefers here and its accurate.

Did u check ur other parameters too? kH levels and Mg does affect Ca levels? what type of salt are u using? some salt may yield low Ca results bt not to ur extent..

Coralline algae uses quite a fair bit of Ca if im not wrong.. correct me if im wrong.

[barnacle]

i heard salifert test kit gave correct reading

but damp $$$$$$

[tineng]

i heard salifert test kit gave correct reading

but damp $$$$$$

no point spending $$$$ on test kits that does not work.....

anyway, i tried to really cheap Sera CA test kit (about 10++ bucks), but the usages is less then what was claimed - used up in 3 months at 1-2 test per week! but for salfiet i get slightly more then 100 tests or last a bit more then 9 months... work out the sum....you will find that over the long run its worth it....

[barnacle]

anyway, i tried to really cheap Sera CA test kit (about 10++ bucks), but the usages is less then what was claimed - used up in 3 months at 1-2 test per week! but for salfiet i get slightly more then 100 tests or last a bit more then 9 months... work out the sum....you will find that over the long run its worth it....

so if you compare btween sera and salifert

which one gave accurate reading??

wats the diff..the reading??

[prec]

dont scrimp on important elements in reefing i guess... one misleading information may just be ur curse.

if u want u can try TM or Salifert. Sera's not so accurate. used it before too when my uncle passed it to me.

[tineng]

you never know if they are accurate unless you have super expensive lab equipment to verify....but salfiert is very consistant....pretty often my hand ichy, I will do 2 tests in one sitting.....salfiert gives consistant results but Sera - quite a number of time very screwy results.....

[prec]

that's what we are getting at bro... =)

[williammuk]

Felix, can you test your Mg and post the readings here? Thanks.

[barnacle]

so there's no test kit in the market that

gave accurate reading, unless we hv

expensive lab equipment to verify....

IMO consistant doen't mean accurate

and screwy result doesn't mean not accurate

it could be the other way round.

test result may vary the way we do it. a little

diff of water and test chemical might lead to a

huge error.

[Felix Wong]

Thanks to everyone for chipping in with the response.

My rocks do have some red coralline algae.

I dont' test the Mg level so I don’t have the results.

However, the pH is always constant (between 8 – 8.5) & the dkH is also quite constant (between 9 – 12). It’s just that the Ca is never constant.

With such low Ca level, I’ve to keep adding Ca powder.

What’s the conclusion based on all these responses?

Get another test kit?

Anyone using X-Glare Ca test kit having the same problem as me?

Those with 2-ft tank (approx 70 – 80L), please share with me your Ca salt dosing frequency and your Ca readings so at least I can have some reference.

Thanks again.

Felix

[tineng]

Those with 2-ft tank (approx 70 – 80L), please share with me your Ca salt dosing frequency and your Ca readings so at least I can have some reference.

Thanks again.

Felix

i use kalk water every night...about 2.5ml spoon of kalk in 30 ml of vingar and 2 littre are tank water then drip in.....

but i'm running a SPS tank with clams...can maintain at about 380-400 CA

when i was without SPS, but with clams and 3 LPS, i dose every other day....

end of the day, even with small tank, how much you dose depends really on what you keep so don't think anyone can give you any concrete advise.....

[williammuk]

Felix, please test your Mg. If I'm not wrong, there is a direct relation between Mg and Ca. Previously, I had a hard time maintaining my Ca when I didn't realise that my Mg was low.

If your Mg is indeed low, then you are wasting your money dosing Ca.

In my opinion, it is better to spend on essentials like reasonably good testkits than to waste your time, energy and money on trying to solve problems without knowing the other parameters.

My $0.02 only ...

[minsmarine]

First , some salt have low in Ca, Mg and Kh. Even for TM Ca is only 370.

So it's could be your salt mix.

Second, if it's salt issue, you should raise up with Calcium Cloride ,( eg Kent's Turbo Calcium ) , so it'll not effect your Kh, Ph and Mg level and test after at least one hour. Not direct to the tank.

Third, we don't know whether your Kh drop/rise after Kawasa drip.

We measure Ca by how much Ca is FREE in water mean no CaHCO3 nor CaCO3. Some time , if Kh is too high ( mean more CO3 ) than whatever you add ( Ca ) will bind with CO3 and become CaCO3. So Kh is very important ( same goes to Mg , also bind to Ca ).

[lightningstrike]

william is right. test ur Mg, if it is 2 low, boost it up. else u wun be able to maintain ur Ca level.

[Felix Wong]

Ok & thanks, I'll test the Mg level. By the way, any recommendation on a reliable & accurate brand of Mg test kit to look for?

And which LFS carries Salifert Ca test kit? Does Aquastar carries it?B]

I more or less also suspected that the carbonate level in the water also affected the Ca reading but did not know how it affected it. Thanks for the explanation.

I read somewhere that corals need both Ca & carbonate so sometimes I add carbonate when the dKh drops to 9 just to bring it to 11 or 12. Is that really necessary?

Worse still, this is affecting my Ca reading and I can't seem to find a trend for the Ca reading after 2 months of weekly testing??

Now I agree that marine fishkeeping is a bottomless pit, keep spending & spending..

Thanks, you guys & gals are really helpful.

[Reefbum]

Bro Felix, first of all changing 30% water is quite a lot for a 2ft tank. Water parameters can go both extreme and this cause your LS to be stressed. Suggest you test your salt mix before you introduce into your tank.

Secondly, test kits are known to have faulty sometimes even those brands that majority of reefers here use.In this hobby you definitely can't skimp on test kits.Try another reputed one to confirm.

Lastly salt mixes are also known to have low Ca.IMO, Ca doesn't deplete so rapidly as in your case with the LS you have unless you add buffers that precipitate the calcium out of the water column.Mg levels does affect the amount of Ca the water can hold.If is low then each time you dose calcium it will precipitate.Hope this helps.

[madmac]

the precipitation if any will result from the binding of pure CaCO3 crystals. Anything less than that won't do. Does your water look clear or cloudy?

it takes only a little Mg to 'poison' the crystals and prevent further precipitation. You should hv enough of Mg as your Ca supplement already has Mg within

even assuming if precipitation/calcification takes place, your carbonates should have gone done proportionally, in your case it is quite stable

i think pH 7.8 to 8.3 is ok....but if you constantly get 8.5, then it is a little too high, the implication is either too much evaporation or your Alk is on the too high side... also don't presume your dKH test kit is ok. A high alkalinity will also make it diff to raise Ca.

you didn't mention what your tank water volume is... the weather has been very dry lately, you jus have to be a bit more careful than those with a larger water volume as evaporation on a small amount of tank volume will be havoc to your parameters

there is an article in Advance Aquarist,

Correcting Ca and Alk Problems

where a problem was posed very similar to yours... excepted from there : "I'm having problems raising my calcium levels above 200 ppm.  I have been using kalk for about two weeks for all top off water, about 3/4 gal a day. The level has never gone above 250 ppm and drops back to under 200 ppm. I bought some Turbo Calcium and tried it as the product label recommended but am having no real success. I have never used Turbo Calcium before and was wondering how much of it I could dose safe. I only have 2 mushrooms and 2 damsels. Any advice?"

you may like to read thru it as it has advices tt you may like to consider using... but pls verify your test kits first and when you hv successfully done it, try implementing a balance solution rather than a two-part separate one tt you use currenlty.

hope that helps, best to you.

[prec]

kalk doesnt raise Ca. it maintains... =) so dont end up buying wrong stuffs bro...

[solo]

Hi,

I've reading up on alk, calcium, mag. requirements but find them rather confusing. Can't really picture clearly their inter-relationships.

Is it possible at all to come up with some sort of visual chart that shows the inter-relationships at a glance?

Gurus, your adv. is greatly appreciated.

Cheers.

[Felix Wong]

Hi, in response to questions asked above,

1. I'm using Tropic Marine Salt Mix.

2. There's no precipitation at all coz if I do add carbonate (I will add only the next day after adding Ca.)

3. When I say I remove 30% of water, I actually meant removing a normal pail of tank water.

4. For evaporation, I do top up every night to the right level.

5. I did not intend to scrimp on test kits but was introduced to X-Glare by the LFS. Experience comes with learning and advice from fellow reefers. Will try better test kits.

6. I believe Ca & Carbonate present in the tank water exists in the free form (not bound or else water will be cloudy), hence can be used by corals but may not be detected by test kit. That's just my assumption so Ca test must be performed prior to adding carbonate (if there is a need to add carbonate).

7. I use Seachem Reef Advantage Calcium which already contains Mg & strontium in the right porportion, would the Mg level still be low and do I need to add Mg separately?

BTW, my tank is 2-ft, guess that's about 75 to 80L.

Rgds. Felix

[minsmarine]

I believe Seachem Reef Advantage Calcium is Calcium Hydroxide.

If it's it, it's just maintain the Ca. By how.

Here is math.

Say, your tank volume is 80L and your topup is 1L.

Your tank Ca reading is 280ppm.

So to boot up to 290ppm ( plus 10ppm ) , you need calcium solution of

10ppm x your water 80L = 800 ppm / L solution.

If you use kalk or lime, their solution is between 380-450ppm so even if you add 1L of kalk water,

balance of 380 - tank ppm 280 = 100ppm/L, which mean your tank water Ca will up for may be 1point, so now 281ppm.

Therorefore you need something like Kent's Turbo Calcium which is Calcium Cloride. It's can have solotion of upto 2,000 ppm/L solution. However, Coloride with contribute to normal salt, so if you add lot, than your SG might go up bit.

Hope it's help

[Felix Wong]

Hi MadMac,

The link on "Correcting Ca and Alk Problems" had some problem. Cannot open webpage.

Thanks Minsmarine for offering advice.

[madmac]

Felix,

"the precipitation if any will result from the binding of pure CaCO3 crystals. Anything less than that won't do. Does your water look clear or cloudy?

it takes only a little Mg to 'poison' the crystals and prevent further precipitation. You should hv enough of Mg as your Ca supplement already has Mg within

even assuming if precipitation/calcification takes place, your carbonates should have gone done proportionally, in your case it is quite stable"

I should also hv been more clear in th statement.... I don't think the problem is due to hte lack of Mg suggestion.. it very likely due to the excess of carbonates relative to your Ca levels.... This can result from either too much evaporation or an overdose.

Sorry, shd hv checked.... thisis the URL : http://www.advancedaquarist.com/issues/nov2002/chem.htm

[Felix Wong]

Thanks MadMac

My water is always clear.

Will read the article that in the link.

Anyone with a 2-ft reef tank, can share how often you add Seachem Reef Advantage Ca salt to your tank (for eg. your response could read 1 tsp (5mL spoonful) on alternate days. For 15% water change, add 2 tsp Ca salt) based on your Ca test?

Thanks.

Felix