New tank with low Mg & Ca?

I have 1110 Mg & 350 Ca in a new tank. Can anyone shed any light on this
for me?

I have drained and cleaned a 240l planted freshwater tank thoroughly with
tap water. Left it to stand and dry for a few weeks in the garage and then
started to set it up as a marine system.

I filled it with (known good) RO water and added Tropic Marin Pro Reef to an
SG of 1.023 (a little low I know). I have allowed this to mix thoroughly
and age for 3 days and was about to add live rock but tested the water
first.

To my dismay the Magnesium and Calcium are much lower than I would expect.
The tank is completely bare except for 3 powerheads, protein skimmer, carbon
& rowaphos in an external filter and the heaterstat. Does anyone have an
explanation for this? The salt has been tested by my lfs and it seems OK.

If I do a 50% water change would this help?

David

By the way, KH is 5, pH is 8.2, Nitrate is 10?! (there is nothing dying off
in the tank, its bare)
I didn't do anything to the RO before I added the salt other than aerate it
for 24 hours as I understand the Tropic Marin should buffer it OK.

Also, I would like to increase the SG to 1.025 as I'm sure this would also
help. What's the best way to calculate how much extra salt should be added
to the water?
---


"David Hillyard" wrote in message
...
I have 1110 Mg & 350 Ca in a new tank. Can anyone shed any light on this
for me?

I have drained and cleaned a 240l planted freshwater tank thoroughly with
tap water. Left it to stand and dry for a few weeks in the garage and
then started to set it up as a marine system.

I filled it with (known good) RO water and added Tropic Marin Pro Reef to
an SG of 1.023 (a little low I know). I have allowed this to mix
thoroughly and age for 3 days and was about to add live rock but tested
the water first.

To my dismay the Magnesium and Calcium are much lower than I would expect.
The tank is completely bare except for 3 powerheads, protein skimmer,
carbon & rowaphos in an external filter and the heaterstat. Does anyone
have an explanation for this? The salt has been tested by my lfs and it
seems OK.

If I do a 50% water change would this help?

David

I do this to calculate the amount of salt to add to increase the SG by 0.0x

Desired SG = 1.25 SG (About 34 Parts Per Thousand)
Current SG = 1.023 (About 31 Parts Per Thousand)

Difference = 3 ppt

Volume of water in tank = Say 200L (You will need to know this)

Therefore each litre of tank water needs 3 gms more (Difference)
so 3 gms x 200 Litres = 600 gms

That's it

GrimReaper

Thanks for the advice. I have now added the extra salt and the SG is up to
1.025.
Ca is now 375, Mg 1170.

My lfs tested a small amount of my salt in RO in case I had a bad batch but
the Ca and Mg readings were a lot higher for him. The test kits I'm using
are brand new and not contaminated. LFS has confirmed my low readings are
accurate.

Having done a little research on the web it seems others have had a similar
experience. I have no substrate at this stage but my lfs doesn't think that
would make any difference anyway.

Would it be a mistake to add live rock with low readings and would it be OK
to add magnesium to bring the levels up or would this cause more problems
later?

Any help is greatfully received, so thanks to GrimReaper.

---

"GrimReaper" wrote in message
...
I do this to calculate the amount of salt to add to increase the SG by
0.0x

Desired SG = 1.25 SG (About 34 Parts Per Thousand)
Current SG = 1.023 (About 31 Parts Per Thousand)

Difference = 3 ppt

Volume of water in tank = Say 200L (You will need to know this)

Therefore each litre of tank water needs 3 gms more (Difference)
so 3 gms x 200 Litres = 600 gms

That's it

GrimReaper

David
I'm not a "Reef" tank expert as such but I would imagine that live rock
would be similar to adding any live animal. You must equalise their
conditions slowly


Regards
GrinReaper

Meant to add
This Forum has massive info on Reef Tanks /Chemistry etc

http://www.reefcentral.com/

You have to register to post but there a lot of section on many aspects of
Reef Keeping including chemistry


Regards
GrimReaper

David Hillyard wrote:
Thanks for the advice. I have now added the extra salt and the SG is up to
1.025.
Ca is now 375, Mg 1170.

My lfs tested a small amount of my salt in RO in case I had a bad batch but
the Ca and Mg readings were a lot higher for him. The test kits I'm using
are brand new and not contaminated. LFS has confirmed my low readings are
accurate.

Having done a little research on the web it seems others have had a similar
experience. I have no substrate at this stage but my lfs doesn't think that
would make any difference anyway.

Would it be a mistake to add live rock with low readings and would it be OK
to add magnesium to bring the levels up or would this cause more problems
later?

Any help is greatfully received, so thanks to GrimReaper.


Just so you know those values are a little low but they are in the safe
range. You can add your liverock without any problems. It is actually
not uncommon for freshly mixed sal****er to be low. You could add a
little bit of epsom salt to the tank to bring up the mag a little, but I
would not worry about it if it was my tank. Once you start dosing your
calcium/alk suppliments you will bring your Ca in line.

Kim
www.jensalt.com

Hi Dave
A bit bored today so I created a single web page calculator to do these
sums. You can enter various SG's and tank volumes.
You can save it to your computer and use as and when


I have put it here

http://www.site266082.fsnet.co.uk/

The password to get in is "saltsums" without the quotes. Its good for ten
days

If you can't get in and want it just ask and I will e-mail it to you


Regards
Grimeaper

Thanks GrimReaper. I've saved your calculator - very useful for a newbie.

On advice of lfs I am doing a 50% water change today to try and raise Ca &
Mg levels but will probably stop worrying too much if it is normal to have
lower readings initially.

Thanks Kim.

"GrimReaper" wrote in message
...
Hi Dave
A bit bored today so I created a single web page calculator to do these
sums. You can enter various SG's and tank volumes.
You can save it to your computer and use as and when


I have put it here

http://www.site266082.fsnet.co.uk/

The password to get in is "saltsums" without the quotes. Its good for ten
days

If you can't get in and want it just ask and I will e-mail it to you


Regards
Grimeaper

Hi GrimReaper,

I tried out your calculator page. If I filled it out correctly using
some imaginary numbers, I would need to add 5016 grams of salt. Now how
many grams come in 1 cup of salt (U.S. measurement) ?

Nice form page.

Marc


GrimReaper wrote:
Hi Dave
A bit bored today so I created a single web page calculator to do these
sums. You can enter various SG's and tank volumes.
You can save it to your computer and use as and when


I have put it here

http://www.site266082.fsnet.co.uk/

The password to get in is "saltsums" without the quotes. Its good for ten
days

If you can't get in and want it just ask and I will e-mail it to you


Regards
Grimeaper


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