Alkalinity

reef_dude76 · 01/25/2020, 10:21 AM

Question, what is the recommended target alkalinity level for our tanks? My slifert kit says that sea water has a dKH between 7-8. What do you all shoot for as a target level? I’ve been testing my levels for the last 4 days and my dKH has dropped fro. 7.3 to 6.9 over that time. The rest of my levels have remained stable. Ph 8.3, calcium 440, and magnesium 1380. Any idea why just the alk is dropping?

bertoni · 01/25/2020, 05:05 PM

7-8 dKH is a fine target. I would target 8 dKH as a starter, to give a little wiggle room for the error limits of our hobbyist test kits. Once alkalinity gets down below natural sea levels, stony coral and coralline algae growth can drop off, and sometimes health problems show up.

A drop of 0.4 dKH units in a few days is a very mild drop. My soft coral tanks would drop 2-3 dKH per day due to coralline algae growth. Lots of tanks run in that range.

garygonzales · 01/26/2020, 10:36 AM

thats where I keep mine as well...if I go higher with my alk it seems my nitrates go up as well...so I keep mine in the 7 -8 range so I can control my nitrates ...

PatW · 02/06/2020, 11:14 AM

I have heard between 7 and 12. Sea water is closer to 7. Most of the acropora venders seem to shoot for 8.0. Some people believe corals grow faster at higher alkalinity. It is generally agreed that keeping ALK levels as constant as possible is the most important thing.

Brieninsac · 02/06/2020, 03:18 PM

My advice is let your salt choice dictate your KH. Don't buy a salt with a dkh of 7 but want to keep it at 9. You will constantly be chasing numbers that way.

coralcruze2020 · 02/10/2020, 10:46 PM

the last post is on point. much easier to do this with choice of salt. i target at about 8 dkh i use red sea black bucket which is at 12 dkh. so i will add that the above post will depend not only on targeted dose but TARGETED DOSE - USED ALK BY CORALS. that of course will depend also on how often you do water changes.

Uncle99 · 02/15/2020, 07:53 PM

There’s not as much Alk in the water at say 140-160ppm, so the change seems normal to me.
Since you used that in 4 days, seems like some dosing is needed depending on your water change schedule

I target 8-9 dkh, CA 430-460ppm, Mg 1360, running a nutrient level of 5ppm nitrate and .1 phosphate.

01/25/2020, 10:21 AM	#1
reef_dude76 Premium Member Join Date: Feb 2005 Location: Maryville, TN Posts: 663	Alkalinity Question, what is the recommended target alkalinity level for our tanks? My slifert kit says that sea water has a dKH between 7-8. What do you all shoot for as a target level? I’ve been testing my levels for the last 4 days and my dKH has dropped fro. 7.3 to 6.9 over that time. The rest of my levels have remained stable. Ph 8.3, calcium 440, and magnesium 1380. Any idea why just the alk is dropping? __________________ She canna take the current captn, she's gonna blow!! Current Tank Info: 20 gallon Nano SPS/LPS mixed reef

01/25/2020, 05:05 PM	#2
bertoni RC Mod Join Date: Mar 2002 Location: Mountain View, CA, USA Posts: 88,616	7-8 dKH is a fine target. I would target 8 dKH as a starter, to give a little wiggle room for the error limits of our hobbyist test kits. Once alkalinity gets down below natural sea levels, stony coral and coralline algae growth can drop off, and sometimes health problems show up. A drop of 0.4 dKH units in a few days is a very mild drop. My soft coral tanks would drop 2-3 dKH per day due to coralline algae growth. Lots of tanks run in that range. __________________ Jonathan Bertoni

02/06/2020, 03:18 PM	#5
Brieninsac Registered Member Join Date: Sep 2015 Posts: 782	My advice is let your salt choice dictate your KH. Don't buy a salt with a dkh of 7 but want to keep it at 9. You will constantly be chasing numbers that way. __________________ Red Sea Reefer 350 (73gal/18gal sump) / Kessil a360WE Lights

01/26/2020, 10:36 AM	#3
garygonzales Registered Member Join Date: Feb 2006 Location: WEST ALLIS ,WI Posts: 922	thats where I keep mine as well...if I go higher with my alk it seems my nitrates go up as well...so I keep mine in the 7 -8 range so I can control my nitrates ...

02/06/2020, 11:14 AM	#4
PatW Registered Member Join Date: Jan 2013 Posts: 275	I have heard between 7 and 12. Sea water is closer to 7. Most of the acropora venders seem to shoot for 8.0. Some people believe corals grow faster at higher alkalinity. It is generally agreed that keeping ALK levels as constant as possible is the most important thing.

02/10/2020, 10:46 PM	#6
coralcruze2020 Registered Member Join Date: Feb 2020 Location: NY Posts: 115	the last post is on point. much easier to do this with choice of salt. i target at about 8 dkh i use red sea black bucket which is at 12 dkh. so i will add that the above post will depend not only on targeted dose but TARGETED DOSE - USED ALK BY CORALS. that of course will depend also on how often you do water changes.

02/15/2020, 07:53 PM	#7
Uncle99 Crab Free Zone Join Date: Sep 2017 Location: Ontario, Canada Posts: 2,906	There’s not as much Alk in the water at say 140-160ppm, so the change seems normal to me. Since you used that in 4 days, seems like some dosing is needed depending on your water change schedule I target 8-9 dkh, CA 430-460ppm, Mg 1360, running a nutrient level of 5ppm nitrate and .1 phosphate.