Alk Problem - been dosing pickling lime

1350

 

Yes, dose to get your alk up. You might consider a PWC to get the Cal down actually. If you have been mixing Instant Ocean RC to salinity of 34-35, then your alk will be high and possibly cal too. Try mixing in 50% RC 50% Sea Salt (SS doesn't have as much Cal and Mag IIRC). Or just do a PWC with only SS.

Usually when I test IO RC @ Sal=35, the Alk is really high, like 12 or 13. So I have a hard time understanding how you have been doing regular PWCs and your alk keeps dropping while your Cal stays the same. Something is not right here. Alk and Cal should get used up at the same rate or roughly the same rate, unless you're running an oversized algae scrubber, and even then it's not always the case.

dripping kalk should keep the alkalinity right, once you have it where you want it. From everything I've read, you shouldn't rely on kalk to raise or lower alk or cal, only to maintain it. Also I've read that kalk won't always maintain Cal, which is why you read about people dissolving the kalk powder in vinegar before adding it to the top-off water or before dosing, as this increases the available Cal content of kalkwasser.

 

Hey there T. If you read a few threads on the scrubber site, you'll see that in certain situations a scrubber will suck down the alk in the system, this supposedly happens when all the CO2 is used up, and the algae then uses bicarbonate to create carbon compounds during the photosynthesis process.

I noticed this effect when I was running an oversized T5HO based scrubber (too big compared to feeding) and I was getting yellow rubbery growth. After switching that tank to the L2 w/LEDs which is smaller, this effect has pretty much gone away from what I can tell, I can dose 6.5 fl oz of BRS Alk into a 5g bucket of RODI on an ATO that pumps about 0.75-1.0 GPD into the system and I maintain Alk right at 9.0 consistently, and then I dose/adjust Cal once a week, usually adding about 10 fl oz to keep it at or around 425. So I may be using a bit more alk, but I was topping off with 1.33 GPD at the same Alk concentration and not keeping up with Alk drop before switching scrubbers.

UAS scrubbers supposedly do not have the alk drop problem, because the CO2 is supplied directly by the air bubbler. However I question the validity of the science behind that theory.

 

I guess it depends on how many stony corals you have - I don't have a huge amount of experience with Kalkwasser. But it makes sense that if you don't have many SPS then dripping kalk may throw off your Cal eventually.