Saltcorner
By Bob Goemans
By Bob Goemans
Hi Bob,
I have a difficult time raising my reef tank's pH level above 8.0. This is a 2-yr old system consisting of a 120 g reef, 40 g seahorse, and a 30 g sump interconnected. The skimmer was removed a year ago when it stopped producing, and I change some water every 4 to 6 months. Except for about 400 lb of rock, including in dark areas of sump and overflows, there is no other filtration, just heater, chiller, calcium reactor, and carbon. There is no detectable ammonia, nitrite, or nitrate. Calcium at 350-400 ppm, and alk at 12 dkh. The oxygen level is normal. The system is healthy with seahorses giving birth every 4 weeks, and all corals, including the acroporas and even gonioporas, growing at a substantial rate.
The ph level starts at 7.78 in am to 7.95 at night. I have never been able to raise this level above 8.0. I have tried Tech CB calcium additive, which has ph buffer, and it only makes a little rise. The calcium reactor's output ph is set at 6.8. When I increase the flow to raise the calcium above 400, the alk goes above 13. Standard ph buffer additive seems to do same. The calcium reactor's output dumps in the overflow's turbulence in the sump with lots of air bubbles. Do you know what I may be doing wrong? Also, with the calcium reactor, I have been adding the complete reef supplement. Should I only add iodine instead? .
Best regards,
MP
California
Hi MP,
Thanks for your email and see two things that should be considered. As for pH being low, I would think your dissolved oxygen level is probably low, which will in turn affect pH. No only is the skimmer a good way to remove nutrients before they have a chance to oxidize/breakdown into pollutants, it also help increase dissolved oxygen, helping to maintain a more acceptable pH level, which should be about 7.9 - 8.0 at night and 8.1 - 8.2 during the aquariums lighted timeframe. Therefore I highly recommend putting a very efficient skimmer into operation, even if it draws little waste gunk out of the system!
The second item is the type/brand of media in the calcium reactor. There are only two that I recommend, i.e., KORALlith media or CaribSea ARM. The reason for this is that other brands/type media have an imbalance between their carbonates and calcium content. In other words, once the majority of calcium dissolves, the majority of the remaining content is carbonates, which will, as they then dissolve, drive up your alkalinity. So, this 'other' media that was 'initially' delivering an ample amount of both calcium and carbonates, is now delivering 'some' calcium and a lot of carbonates as it ages in the reactor and/or as you increase the flow or CO2 bubble rate. In fact, any time this sort of thing happens, its time to change out the media, even if the reaction cylinder still looks quite full! The true initial value of the media has been exhausted, therefore its time to change it out. And believe me when I say I've gone through this sort of thing many times until I changed over to the brands mentioned!
Hope this helps,
Bob
