2 part dosing help

ChaseBurke · Sep 17, 2019

So I have 90 gallons total system volume. Was dosing 100ml of brs soda ash at 9 every morning. And testing at 8 at night. My alk drops to 7.3 when I test and have to add about 45 ml to get back up to 8. I changed my dos to deliver 150ml spread out over 24 hours. Is it ok to dose over 24 hours and should I dose the 100 or 150ml?

Ron Reefman · Sep 17, 2019

Dosing smoothly over 24 hours is the best possible way, but even dosing once a day (that's what I do) isn't as bad as some make it out to be. Also sps are more upset by parameter changes than zoas.

I'd dose 100ml and keep trak of the alk level twice a day for a few days. If the alk level holds, you're good to go. If the alk level slowly goes down, bump the daily level up some. IMHO it's better to start low and see the alk level go down some so you can adjust the dose up than the other way around.

Randy Holmes-Farley · Sep 17, 2019

It is fine to spread the dosing out. The amount you should dose depends on your target alk level. Determine the amount it takes to maintain the alk target, and dose the same amount of calcium, at least for a while until you see long term calcium trends.

ChaseBurke · Sep 17, 2019

Calcium I have dialed in. It’s my alk lately that has been giving me problems. Wonder if it’s starting to precipitate out. I went with the 150ml on the dos last night spread out over 24 hours. Tested at 10 this morning and was at 7.9 and again at 9:30 and was at 7.7 How much alk do you think my tank should be using to keep at 8.0?

Ron Reefman · Sep 18, 2019

ChaseBurke said:
Calcium I have dialed in. It’s my alk lately that has been giving me problems. Wonder if it’s starting to precipitate out. I went with the 150ml on the dos last night spread out over 24 hours. Tested at 10 this morning and was at 7.9 and again at 9:30 and was at 7.7 How much alk do you think my tank should be using to keep at 8.0?

If you are dosing over a 24 hour period it's very UNLIKELY that it is precipitating out. Especially if the alk level is under 8.0dKH.

It's virtually impossible to calculate how much you should dose other than dosing, seeing how much your alk level drops over time (2 to 4 days) and seeing how much alk you need to add to get it back to where you started (and where you want it). If 150ml wasn't quite enough, dose more.

Question for you. You have a 90g tank, but what kind and how much coral do you have? A FTS (Full Tank Shot) of your tank might be helpful. I have a 40g cube that is 85% zoas, soft coral and anemones, none of which use much alk at all. The other 15% are lps and sps and I dose about 50ml per day.

Randy Holmes-Farley · Sep 18, 2019

ChaseBurke said:
Calcium I have dialed in. It’s my alk lately that has been giving me problems. Wonder if it’s starting to precipitate out. I went with the 150ml on the dos last night spread out over 24 hours. Tested at 10 this morning and was at 7.9 and again at 9:30 and was at 7.7 How much alk do you think my tank should be using to keep at 8.0?

Alkalinity only precipitates out with calcium.

Tank vary widely in the alk needed. 0.5 to 2.5 dKH per day is fairly typical.

ChaseBurke · Sep 19, 2019

Thank you guys. I think i have it pretty dialed in now at 170ml per day. i think the reason i was concerned was because i switched from Triton Cor7 to the brs 2 part. I forget the cor7 is pretty concentrated. But will post a FTS when the lights come back on.