High Ph and Low Kh

[sun2000]

My tank is suffering from unusually high ph (8.5 measured with calibrated probe) while my Kh is getting lower and lower (measure 7.3 dkh using Salifert (new)). Calcium is OK 400 and Mg is OK 1400. NO3 0 and PO4 0 measure using Salifert. Done 2 water change (120l each time) but problem still there. Ph will come down but after a while it will climb back up. During night Ph drops to 8.2 only. Took a sample out and ran an air pump thru it to see if Ph will come down but after 1 hour the drop is negligible. If I dose Vinegar to bring it down, it impacts my Kh even further. I am dosing 2 part CaCl and NaHCO3 but stopped for over a week.

Tank is lightly stocked ( 4 anthias and 1 flame angel) for 5ft x 2 x 2.5 ft and mixture of LPS and SPS and several RBTA. .

I am in a tough situation . If I dose Sodium Bicarbonate to raise my Kh to 8.9, my Ph goes off the chart. If I leave it as it is, My Kh keeps dropping and at 7.3 I am worried it is too low. So to anyway to raise Kh while not raising Ph or lower Ph without impacting Kh?

Appreciate any help from the anyone here with experience on this

thanks

[thomas_lim]

7.3 is still ok but not below 7.

You can try using baking soda or Kent Coral Builder.

All the best

[asg]

Bro, what salt u using...

[POTO]

I use kalk sometimes to boost up my kh.

[POTO]

Ph* I mean

[sun2000]

Thanks everyone for your inputs. I am using Skimz salt and changed over from H2O a few months back. It has been fine for a while ( 6 months at least) but problem only came about 1 month ago. Not sure why. A lot of Calcium precipitation in the tank on on my pumps and skimmer as the Kh dropped and could not hold the Calcium level in the tank steady. Killed my Skimmer and had to change the impeller. I've just gone thru cleaning all my wave makers and return pump and piping( Calcium deposits) and calibrating my Ph meter as well as bought a new batch of test kits to ensure the problem was not due to a measurement problem. I start the morning and Ph is already at 8.2 and this will climb slowly to 8.5 and sometimes beyond. At 8.5 you can see the Hammer, Acans and Zoa all not happy ( not extending fully) and SPS still showing some PEs, no visible problem but I notice the PEs are less. Obviously stressed but still hanging on ...but for how long.

Want to know how to increase KH from 7.3 to above 8 and reduce Ph to around max 8.3. Adding Baking Soda or Sodium Bicarb increases Kh but also increases PH.... I need to balance first before I can increase. Right now no idea how. Looking for advise from anyone.

[asg]

bro, when you say KH 7.3 is actually dkh 7.3, right?

dkh 7.3 is fine, ca 400 is also fine. Why not you stop dosing anything and just do regular WC for the next one week or two and monintor your PH and dkh every morning and late evening to see the trend...

[sun2000]

Yes I mean 7.3 dKh and I have stopped my dosing for over a week now and original dKh was 8.9 and continue to drop by 0.3 daily but Ph remains high.Lowest in a day was 8.2 and that is early morning and then evening 8.5 to 8.6 varies a bit. This is without dosing Sodium Bicarbonate. If I dose 15g (diluted in 500ml) thru the day( 50ml each time via dosing pump) the Ph goes even higher to 8.6 and above so had to stop. Not sure which is worse low Kh or High Ph.. Will continue to monitor but if dKh drops to 7 I'll do water change and see.