View Full Version : 2 Part Dosing help

03/31/2013, 01:12 PM
Ok so I just got setup with 2 drews dosing pumps ( 1.6 ml per min) and added them to my reef keeper lite. I mixed teh solutions as instructed on brs and began dosing. It quickly became apparent that my tank was requiring teh alk pump to be on for 6 min every hour where as my ca pump only needed 2 min per hour. I thought this sounded out of whack so I contacted BRS. THey are very helpful but im not sure the advice im getting is correct, so im running it by all of you jedi masters. THEy instructed me to turn off all dosing pumps for 4 days total. they said wait 24 hours after turning the pumps off and them measure your levels. I did this and got these results. Ca was at 500, ALk was at 7 DKH. Mg was at 1400. I just took my levels on day 4 and now DKH is at 5.3 and ca is at about 480. THese levels indicate that my tank does indeed use far more alk than ca. BRS said I should be using the same amount of each additive in terms of soda ash and calcium chloride. When I look at the usage on teh calculator I will need to use about 5X as much Soda ash as Ca to bring my levels back to where they were. SO i guess im using 5X as much DKH as CA.. what am I DOing wrong? I dont think teh dosing pump will last long at 5 min per hour and on top of that from everything I have read the dosing of each should be at least close and not 5 to 1 .

03/31/2013, 04:14 PM
Okay, first of all, I would never, ever stop dosing for 4 days in a tank that consumes a lot of alkalinity. When the dKH drops that low (5.3), stony corals can start having problems. It's also useless, because the alkalinity consumption rate varies with the dKH level, so you don't even get good data.

I would dose the dKH up to 7 dKH or so with some baking soda right away. Later today, I'd measure again and bring it up to 8 dKH. This calculator will help with a dose:


I'd then start measuring alkalinity and dosing the two-part by hand at the same time each day, or maybe twice a day if the consumption is high. After a few days or so, you should have a good trend line for alkalinity.

Calcium is harder to manage because there's so much more of it in the water, in terms of making calcium carbonate. 2.8 dKH is consumed for every 20 ppm of calcium. I'd probably test the pumps to make sure that they are dosing the same amount, and let them run with your computed dose for a while, perhaps checking calcium and alkalinity every day for a few days, to make sure the pumps are okay. After a while, you should get a good trend line for calcium, although it might take a few weeks.

Calcium kits often are good only ±20ppm or so, so some patience is required.

03/31/2013, 04:24 PM
I forgot to mention that pH buffers all add alkalinity, despite any marketing claims, and tap water can, as well. Is anything else being dosed into the system?