having trouble getting alk up

I have been having a real hard time getting my alk up over the past week, been trying to get it dialed in and learn my take up. I have tried using baking soda in di water and seachem part 2 dosing according to the calculator but it just wont come up. It seems to come up for a couple hrs but the next day it's right back down to the level I started with the day before. Seems this would be the daily dose to keep it up however the calculator says this is the dose to get it up to the desired level.

75g DT drilled, plenty gas exchange 16g sump, 40g fuge- yes 40g lol
8g wc every week last one yesterday 10:00 am / DI filter system
age of system 11 weeks cycle complete
Load is one coral beauty, 3 star- target feed, very small cuc
time 8:00am temp 76.5 sal 1.026
mag 1450 -dose brs 2 part
alk 2.8 trying to get at least 3.4 and in a 24 hr period/ .5 per day
cal 540 - not dosing, high but this is the current level mixed up in can using seachem reefsalt.
ph 8.08 -low in mornings, lights not on very long in DT or refuge because of diatoms.
phos. .01
trites 0
trates < 1

running dual reactor 24/7
1cup gfo
rox carbon

started ato yesterday with 2 tsp per gallon mrs. wages

still have small diatom bloom, wish silicates would get used up!!

Anybody see anything or sugestions?

 

Do you have a lot of hard corals or coralline algae? On your kalk ATO, are you using a restricted, slow pump to "drip" it, or squirting it in at once.

There are only 3 reasons you would see a drop like that.

1) Organisms are using it. Hard corals and coralline algae use quite a lot. My tank for example, drops over 1.5dkh per day (approx 0.5 meq/q). Heavily stocked SPS tanks, with lots of coralline can easily drop 3+ dkh per day.

2) abiotic precipitation - adding a lot of GFO, or something with a clean surface area could lead to abiotic precipitation. Also, raising the pH too high or too fast will cause abiotic precipitation. For example, if you add limewater too fast, or add too much alk buffer at once. This can cause precipitation or if extreme, a precipitation event. In this case, the alk can actually drop lower than it was to begin with.

3) testing error. This is quite common as hobby grade test kits are made to be cheap, not good. Seachem reef salt mixed to 540ppm and 10dkh. Your at 540 ppm, but about 7.8dkh. This is a bit odd, typically anything that will bring down alk will also bring down ca, there are a few exceptions though. For example, adding extra ca can drive down alk. I would definitely try some other kits though, and rule out testing error. It's also possible that ca is dropping, but ca drops slow in proportion to alk, so maybe the ca test kit your using just isn't sensitive enough to detect the change.

Here are some good articles:
When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley - Reefkeeping.com
A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH by Randy Holmes-Farley - Reefkeeping.com
Calcium and Alkalinity by Randy Holmes-Farley - Reefkeeping.com

 

Have you triend the BRS alk dosing stuff? That is what I use and normally cut the dosing in half for the morning when i add it then also at night start another drip to get my alk to stay as stable as possible at 9dkH

 

If you are not using one a hanna alkalinity checker is worth a look. Very accurate and easy to use.
Checker®HC Handheld Colorimeter - Alkalinity, HI 755 | HANNA Instruments

 

No corals, reef tank is what im trying to achive but tank is to new and no batt back up yet.
Slow drip method of ato, using brs kit with aqua lifter pump

Think i'm going to cut out the gfo for a little while and watch the phos level, I've read on here gfo can mess with it and you also give that as a reason. Will also read these articles
Thanks

 

You can try cutting back the GFO. You may not need to cut back on GFO though. It's really only "fresh" surfaces that allow abiotic precipitation. Once the precipitation has occured and the surface is contaminated, the precipitation should slow and/or stop.

 

No, not using there alk, had some other alk and baking soda so wanted to try that first. I just bought there cal and mag dose in a group buy, should have got the alk also. I love there stuff.
Thanks

 

Using seachem reef status mag and alk test kit,using nutrafin cal kit. Both lfs were out of salifert, seems they could keep more on hand :-/
Will try again to see if they have any in.

 

No, want one but didn't know if there worth it. Will save money over the long haul but most important you say there accurate!!!