Can not keep up with alkalinity consumption

[sig_1959]

Two months ago slowly increased alkalinity from 6 to 9 (using Seachem carbonate) and started to drip Kalk, but looks like my tank consume carbonates in big values, and I was not able to to keep it even at 7.
Last week started to use Soda Ash and was continue to drip Kalk. The PH was increasing at the moment of adding Soda, but in few minutes it was going back to 8.2. This is normal as per RBS instructions.
At the moment, I stop to add Soda Ash (using Part 2 pouches) and continue to drip Kalk after 2 days alkalinity again 6 and PH is 8

salt is Reef Cristal
Calcium is 440.
20G weakly whater change.
I mix 10 tea spoons (with top) per 3G of rodi and drip it within 3-4 days.
Current system total is 170G
Most of my corals are SPS and LPS, but they are not big ones.
The tank is 10 months old
I have no clue what is going on

I am attaching image just to provide info how full is the tank
Thank you guys for advice

 

[EdSnyder]

Really nice looking 10 month old tank! Dang. I can increase alk to dangerous levels if I want adding 2 part. I would stop with the kalk, and just dose alk, part of 2 part.

 

[sig_1959]

Thanks Man,

Was thinking about it

 

[RA]

Really nice looking 10 month old tank! Dang. I can increase alk to dangerous levels if I want adding 2 part. I would stop with the kalk, and just dose alk, part of 2 part.

Why would you recommend to stop with the kalk? The kalk will keep the tank stabilized better if used in an ATO. Then he could adjust once or twice a week with 2 part to increase Alk or Calcium to the desired level. Works well for a lot of us.

 

[Randy Holmes-Farley]

I think using some two part in addition to the limewtaer (kalk) is a fine plan to maintain alkalinity and calcium.

 

[HV1990]

when your dosing 2 parts are you doing it all at one time or spread out the day. Reason I ask is it may be your ATO is slowing down the spikes but not enough. More dosing throughout the day may be a better solution.

 

[sig_1959]

Thank you guys. I do not get why my calcium is always normal and Alkalinity is low.

I think I will switch from the KaLk just to Soda Ash and see what happens.
Thanks again

 

[sig_1959]

when your dosing 2 parts are you doing it all at one time or spread out the day. Reason I ask is it may be your ATO is slowing down the spikes but not enough. More dosing throughout the day may be a better solution.

It could be because evaporation volume is not always the same

 

[Randy Holmes-Farley]

Thank you guys. I do not get why my calcium is always normal and Alkalinity is low.

I think I will switch from the KaLk just to Soda Ash and see what happens.
Thanks again

That is always the way if you underdose both equally. The reason is that there is a huge reservoir of calcium in seawater relative to alkalinity.

If you start at 8 dKH and 450 ppm calcium and let calcium carbonate be deposited with no dosing, you can attain 6.6 dKH and 440 ppm calcium. That alk drop looks huge and the calcium drop looks within the error of testing.

 

[sig_1959]

Thank you very much Randy. Finally after two weeks I found the answer to my problems
Greg

 

[GPB]

Listen to Randy , he is the man on such topics. He has never steered me wrong.

Thanks for all the advice Randy!