Should I be dosing

P

paulsz

New member
Hi all,

I have a 35 gal cube with a 20 high sump (filled about halfway), so total of ~40 gallons. Finished cycling a couple of months ago and I have two fish and 4 soft corals at the moment. I have a zoa frag (6 heads), sympodium frag, mushroom and GSP frag.

I know these sofites don't generally need dosing, but i tested my water for the first time two days ago and I got the following readings (using salifert tests):

Calcium = 360 ppm
Alk = ~6.85 dKh
Mag = ~945 ppm

Some info on my tank/maintenance:
-my pH is a little low for a reef tank, at about 7.8
- 10-15% weekly water changes
- i use red sea coral pro salt

I heard that raising Mag will help raise Cal/Alk levels... is that true? Any suggestions on what I should try?

Thanks
 
paulsz said:
Hi all,

I have a 35 gal cube with a 20 high sump (filled about halfway), so total of ~40 gallons. Finished cycling a couple of months ago and I have two fish and 4 soft corals at the moment. I have a zoa frag (6 heads), sympodium frag, mushroom and GSP frag.

I know these sofites don't generally need dosing, but i tested my water for the first time two days ago and I got the following readings (using salifert tests):

Calcium = 360 ppm
Alk = ~6.85 dKh
Mag = ~945 ppm

Some info on my tank/maintenance:
-my pH is a little low for a reef tank, at about 7.8
- 10-15% weekly water changes
- i use red sea coral pro salt

I heard that raising Mag will help raise Cal/Alk levels... is that true? Any suggestions on what I should try?

Thanks
Click to expand...

I'm just into the same area that you are in! I'll give you the advice I was given.

Do a water change of your normal size, then wait a few hours and test your metrics. Wait a week without adding/dosing and test again. This tells you how much your parameters change within that one week, and will serve as a great guideline to help you dose.

That being said.

Your mag is low. Your alk is low. Your calcium is low. You don't seem to have a super overstocked tank. What are you using for salt? EDIT: You answered me!

When you make up your normal batch of waterchange water, do a test of the mag/calc/alk/ph of just that batch by itself, before adding it to the tank. With the S.G correct of course. This will give you a benchmark of what you are adding, so you know if your tank numbers have fallen from where a water change can get you.

Edit:: Your salt should be: KH - 11.8-12.2 °dKH, Ca - 430 - 450 mg/l, Mg 1280 - 1340 mg/l.
 
Last edited:
I wonder if your salinity is low. How are you measuring it?

Salinity should be about 35ppt (1.026 on the specific gravity scale).
 
Levels are definitely low. You won't need to dose with a whole four corals. Do a bigger water change than normal, see if that brings levels up, it should. You could dose mg, a stable level around 1350 will serve to stabilize the other two.
 
sde1500 said:
Levels are definitely low. You won't need to dose with a whole four corals. Do a bigger water change than normal, see if that brings levels up, it should. You could dose mg, a stable level around 1350 will serve to stabilize the other two.
Click to expand...

Okay sounds good. I will also follow the below and test my new water before putting it in the tank.


When you make up your normal batch of waterchange water, do a test of the mag/calc/alk/ph of just that batch by itself, before adding it to the tank. With the S.G correct of course. This will give you a benchmark of what you are adding, so you know if your tank numbers have fallen from where a water change can get you.
Click to expand...
 
Rover88 said:
I'm just into the same area that you are in! I'll give you the advice I was given.

Do a water change of your normal size, then wait a few hours and test your metrics. Wait a week without adding/dosing and test again. This tells you how much your parameters change within that one week, and will serve as a great guideline to help you dose.

That being said.

Your mag is low. Your alk is low. Your calcium is low. You don't seem to have a super overstocked tank. What are you using for salt? EDIT: You answered me!

When you make up your normal batch of waterchange water, do a test of the mag/calc/alk/ph of just that batch by itself, before adding it to the tank. With the S.G correct of course. This will give you a benchmark of what you are adding, so you know if your tank numbers have fallen from where a water change can get you.

Edit:: Your salt should be: KH - 11.8-12.2 °dKH, Ca - 430 - 450 mg/l, Mg 1280 - 1340 mg/l.
Click to expand...

^ This. I second that everything is a little low so first check the Salinity in the tank now. If it is on par, you should have no prob doing a 50%WC (20g). Then follow the steps above. If not a large WC should correct values. Correct Mg first if a large WC does not bring it within the normal range.

I suspect with a softie tank consumption will be low so you may find a benefit in waiting two weeks before doing the second test. This will give you more substantial values to work with.
 
paulsz said:
i tested my water for the first time two days ago and I got the following readings (using salifert tests):

Calcium = 360 ppm
Alk = ~6.85 dKh
Mag = ~945 ppm

Some info on my tank/maintenance:
-my pH is a little low for a reef tank, at about 7.8
- 10-15% weekly water changes
- i use red sea coral pro salt
Click to expand...

do another test, make sure to follow the instructions carefully.
take some tank water to your local LFS and have them test it.

those results almost look like they are the result of bad testing.

test water from a freshly mixed up batch. does that test to the levels your salt mix should have?


J.
 
I agree that it's a good idea to double check with a LFS for:

salinity
Mg
Ca
Alk

Testing your makeup water is also a good idea.

With Mg that low...either your salinity is about 20% low, or you got a bad batch of salt.
 
Sounds good :) Thanks for the quick help everyone. Much appreciated. I'll test a fresh batch of SW tonight
 
Here is the simple answer you needed..

You dose when your current water change schedule is not sufficient to keep your parameters stable enough due to consumption by the life in the tank and you do not want to increase your water change schedule to adapt to that..
plain and simple..

BUT.. you need to ensure your readings are accurate first.. I kind of doubt they are OR you haven't done a water change in a while..
 
I agree with getting a second opinion on some of the test results, particularly the SG. Those numbers seem consistently low, which might indicate that the SG is lower than your device is indicating. It's hard to be sure at this point. If any animals are in trouble, getting an SG reading would be the first step, followed by some water changes, as needed.
 
I checked my SG and it is closer to 1.024. I have added salt to my ATO and will replace with freshwater once I get to y desired 1.026. One issue i'm having is with calibrating my Red Sea refractometer. I use RODi water (0 ppm) to calibrate it at 0 but almost every week during my WC, it needs re-calibration because my RODI will end up under the 0 line by a bit. I will take some of my tank water to the LFS and see what they get as results for Cal/Alk/Mag.
 
paulsz said:
I checked my SG and it is closer to 1.024. I have added salt to my ATO and will replace with freshwater once I get to y desired 1.026. One issue i'm having is with calibrating my Red Sea refractometer. I use RODi water (0 ppm) to calibrate it at 0 but almost every week during my WC, it needs re-calibration because my RODI will end up under the 0 line by a bit. I will take some of my tank water to the LFS and see what they get as results for Cal/Alk/Mag.
Click to expand...

I use the same refractometer. If you read the manual, they state you MUST calibrate it every single time that you use it.

My suggestion is to do so. Put some RODI on it, wait about 30-45 seconds for it to temperature correct, and then calibrate it to the line. I don't trust it unless I do this, as it never holds a calibration. And I mean /never/. I can put it down, pick it up an hour later, and its off.
 
I would also get some 35ppt calibration fluid. Even if you are calibrating with RODI, I would suggest using a known 35ppt as a "check standard."
 
nereefpat said:
I would also get some 35ppt calibration fluid. Even if you are calibrating with RODI, I would suggest using a known 35ppt as a "check standard."
Click to expand...

The red sea refrac/manual specifically states DI water and not 35ppt cal fluid..
For the red sea DI water is the proper calibration fluid..
 
mcgyvr said:
The red sea refrac/manual specifically states DI water and not 35ppt cal fluid..
For the red sea DI water is the proper calibration fluid..
Click to expand...

That's fine. But after calibrating with the DI water, measure the 35ppt standard and make sure that it reads 35ppt = check standard.
 
Looks like faulty tests. Got a new kH test kit from my friend and tested it on the new water that i'll be putting in today (weekly water change). Got these results:

kH (with the new kit): 12
Mg (old faulty kit): 990
CA (old faulty kit): 400

all this at salinity of 1.026 and pH of ~8.0-8.2

looks like I'll have to get a new Mg and Ca kit.
 
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