Confusion about raising alkalinity

[brian222]

Hi reefers,

I have spent some time doing research online and on R2R about how to raise alkalinity in my tank. The reason I want to raise the alkalinity is that it is often below 7 dkh (before water change it is usually around 6.8). I have some sps and lps corals in my system now so I would like to slowly increase my dkh to give them an environment that has parameters as close to nature seawater as possible. My parameters:

Salinity: 1.025
Alkalinity: 7.0 dkh
Calcium: 480 ppm
Magnesium: 1260 ppm
Nitrate: 3ppm
Phosphate: ~0.01 (3ppb phosphorus * 3.066/1000 from Hanna ULR Phosphate)

The questions that i have:

1)I got myself the BRS 2 parts kit with 3 mixing jugs, I use the BRS calculator and it shows i need 20 ml of soda ash solution to raise my alkalinity from 7.0 to 7.5 dkh, do I need to dose equal amount of calcium chloride to maintain the balance?

2)do I need to raise my magnesium to help with dosing soda ash and calcium chloride? If so should I raise my Magnesium first?

Sorry for my long post and many thanks in advance from a noobie

 

[Skynyrd Fish]

It looks like you are in a good place with your water. You could bring up your mag to 1350, and slowly bring up alk to 7.5. However to CA is a touch high so let it fall naturally. It may take a couple of days. Again your water is in a good spot now. Nothing wrong with 7.0 alk. Once you get your alk and ca where you want them it should be equal amounts dosed at that point with occasional corrections.

 

[brian222]

It looks like you are in a good place with your water. You could bring up your mag to 1350, and slowly bring up alk to 7.5. However to CA is a touch high so let it fall naturally. It may take a couple of days. Again your water is in a good spot now. Nothing wrong with 7.0 alk. Once you get your alk and ca where you want them it should be equal amounts dosed at that point with occasional corrections.

Thanks for replying! I am going to dose 0.05ml soda ash solution per day over 4 days to try to slowly increase my alkalinity a little everyday, however I am not sure how much the calcium level will go down if I increase alkalinity.

The guy in my LFS told me I should increase my alkalinity to the desired level first then take care my calcium, the last thing I want is to introduce volatility to my parameters. So I do not have to dose calcium chloride when I increase my alkalinity?

 

[Skynyrd Fish]

I would slowly raise alk and test ca. Once ca hits your desired level, start adding ca to maintain.

 

[PatW]

Just add the alkalinity. At 480, your calcium levels are plenty high. For alkalinity, the rule of thumb is to not change by more than 1 DKH per day and less if you can get away with it. A thriving SPS tank can easily consume more than 1 DKH of alkalinity per day. People in this situation often resort to automatic dosing.

 

[maroun.c]

0.05 is kinda too small to measure.
I'd do the correction slowly, wait for ur ca to drop while dosing small doses of alk to maintain then start doing Ca, as the solutions are calibrated they should match consumption at equal doses but shifts do happen. U can add small doses if mag to minimize drops or can correct every few weeks after small drops as mag drops slower.