Alkalinity

[labnjab]

Either we have 2 bad test kits our our alkalinity really is low. We're using 2 api alk test. I keep getting a reading of 6 alk while our calcium is 400 and our magnessium is 1400. With those mag and calcium lvls our alk should be 8 or 9. We have a calcium reactor which is set at 1 drip a second with 1 bubble every 4 seconds co2. The effluctant ph is 6.65 which is perfect and the effluctant alk is well over 12. Were using carib sea Arm media which is suppose to be one of the best. We also drip kalkwasser at night to keep the ph stable.

It just doesn't make sense and its been driving me absolutely nuts because our ph stays stable, goes to 7.95 during the day and only drops to 7.8 at night. Stonies and coraline grow like weeds but the alk always test low. I wouldn't think it would be the test kit because if we dose buffer it goes up but then drops back down after a few days

Any suggestions? I always heard the api test kits were one of the better alk kits so I'm assuming our alk really is low but how?

[kaimarkhirst]

Reef chemistry reads like this.

during the day alkalinity should remain aroung 12 dkh and drop to 9 at night presenting the variable of the clacium carbonate breakdown. If the magnesium is that high then the alkalinity is going to be low as the magnesium levels in your tank are largely preventing the precipitation of calcium carbonate in the chemistry of the water. So the alkalinity is going to be low as your magnesium levels are preventing the formation of calcium carbonate, so there is a low buffer ratio because of this.. Your ph is low specifically because the calcium reactor is feeding too much co2 in the tank, driving the ph down to break down the calcium ions in your reef.

I dont have a calcium reactor, and manually dose all ions and supps to the water. My readings are this.

Ph 8.1 all day and night. This should never change more than .02 or so....
dkh 11.8-12 day, 9-10 night...
Calcium 450 all day long and 425 night...

Dont need to measure mg, i let the salt makeup sort this out for me...

In essence your makeup is way too complicated but thats just my opinion, but more specifically, your co2 feed is too much on your calcium reactor. Reef chemistry changes constantly during the day and night and are made up of many variables and what your trying to do is keep all the variables that are key to a stable reef a constant by driving co2 to increase buffering capacity, and then drip kalkwasser to stablise the ph and buffering at night. You cant do this and have to let the chemistry take its course. Reduce the co2 or get a ph controller to do this, then drop the kalkwasser. see what happens. Youll be surprised...

Hope this helps.

Kai

[labnjab]

Thank you for your help. Sorry it took so long to get back to you. I made a few adjustments and alkalinity is back up and holding steady. We have the reactor on a ph controller which shuts down the c02 when it dips below 7.79 and its been weeks since its been that low. Currently its sitting at 7.85 and the lights have been off for 9 hours. Alk its back up to 9 right now and I'm sure it will be higher when I measure tonight. I have even seen an improvement in coral growth which is hard to believe since they were already growing like weeds.

[kaimarkhirst]

i wasnt expecting you to come back soon mate as this one is a complicated problem...

Its good that theres an improvement on this, but its still low.... (unless that alk meaaure is at night, then your sort of ok..) and im glad to see that youve invested in the one piece of kit that is essential to calcium reaction tech, which is a ph controller.... Excellent...

Ideally you want to set your controller to go off at 8:2 and come on at 7.9 or 8.0 if you can be this precise as this will put the buffer at 11.5 in day, and 10.5 at night roughly.... Your magnesium should stay at 1300 and calcium should read around the 425-450 mark.

What will happen here then is proper calcification can occur within corals, theyll stop looking like floppy weeds, and you will get some great growth and reef growth.

There was an article on reef chemistry in an issued of practicle fishkeeping. Ill scan, upload for all to see if anybodies interested? Or you should be able to google this. It is a bit chemistry project, but a good learned read none-the-less