Alkalinity Consumption

[phinatic]

My tank is taking up more alkalinity than I would expect. Tank is a Fluval Evo 13.5G. Wanted to run some numbers by the forum and see if they seem to be in range. The dosages are in the last column. The "3-ion" is a Ca/Mg/Sr supplement. I added some frags on 5/24 but they are all pretty small, and I wouldn't expect them to use this much Alkalinity. I don't have visible coraline algae in the tank. Test are all color matching drip tests. Other than 5/23, all dosages were done after recording measurements. On 5/23, I tested before and after a large dosage to get alkalinity up before adding frags.

 

Alkalinity Dosing Instructions

Add 10 mL per 50 L (13 US Gal) once a week. Weekly dosage provides 0.5 meq/L (25 mg/L) of alkalinity.

 

3-Ion Dosing Instructions

Add 5 mL per 40 L (10 US Gal) once a week. Weekly dosage provides 10 mg/L of calcium, 1.5 mg/L of magnesium and 0.2 mg/L of strontium.

 

 

	Temperature	Salinity	pH	Alkalinity	Ammonia	Nitrite	Nitrate	Phosphate	Calcium
Target	TRUE	TRUE	TRUE	FALSE	TRUE	TRUE	TRUE	TRUE	TRUE
Current	79.000	1.026	8.100	134.000	0.000	0.000	0.000	0.000	380.000
6/5/2023	79.000			134.000					380.000
6/4/2023	79.000		8.100	125.000					400.000	Alkalinity 10 ml
6/3/2023	79.000		8.200	125.000					380.000	Alkalinity 7 ml
6/2/2023	79.000			152.000					370.000	3-ion 7 ml
6/1/2023	79.000			143.000			0.000	0.000	390.000	Alkalinity 5 ml
5/31/2023	79.000	1.026	8.100	152.000					400.000	3-ion 5 ml
5/30/2023	79.000		8.000	143.000			0.000	0.000		Alkalinity 5 ml
5/29/2023	79.000		8.100	152.000	0.000	0.000	0.000	0.000	380.000	3-ion 5 ml
5/28/2023	79.000	1.027		143.000						Alkalinity 5 ml
5/27/2023	79.000			161.000
5/26/2023	79.000			152.000
5/25/2023	79.000	1.027	8.100	143.000						Alkalinity 5 ml
5/24/2023	79.000	1.027								Added 9 sps frags
5/23/2023	79.000			179.000						Alkalinity 20 ml (143 prior to dosage)
5/22/2023	79.000		8.100	125.000	0.000		0.000	0.000	400.000	Alkalinity 5 ml

[phinatic]

I've been using Fluval Sea supplements but plan to switch to Tropic Marin All-For-Reef this week after getting a handle on the uptake.

[phinatic]

One more note. I had a pretty consistent uptake prior to 6/3. On 6/2, I switched to the Saxby lighting model that is heavier with UV and purple than my prior light model. I assume that has caused more growth in the frags. Just seemed sudden.

[seabass]

I didn't really go through your numbers, but:

15 hours ago, phinatic said:

Alkalinity Dosing Instructions

Add 10 mL per 50 L (13 US Gal) once a week. Weekly dosage provides 0.5 meq/L (25 mg/L) of alkalinity.

those weekly dosing instructions are just arbitrary numbers that would be right for a relatively small percentage of reef tanks.  However, it does provide usable dosing numbers (with a little math):  10ml adds 0.5 meg/L.  It looks like you are using ppm CaCO3 equivalent (which is fine), although dKH is used more often, and your alkalinity supplement is using meg/L.

 

Recommended alkalinity levels:

2.5-4 meq/L
7-11 dKH
125-200 ppm CaCO3 equivalents

 

When dosing alkalinity, you should also know your magnesium levels, as low magnesium could cause precipitation of alkalinity and/or calcium (especially when dosing).  But you're right, small frags usually only consume small amounts.

 

I did notice that phosphate was undetectable.  Ideally, for your corals, phosphate should be at least 0.03ppm.

[phinatic]

4 hours ago, seabass said:

I did notice that phosphate was undetectable.  Ideally, for your corals, phosphate should be at least 0.03ppm.

Yeah. It's "0" on my kit, but I don't have a low end test kit. The next step up on my kit is 0.25 for phosphate. I'm sure I am in between somewhere. Same goes for Nitrate, but I know it's in there based on my feeding and macro growth. I keep cutting back the macro and it keeps getting bigger :)

[phinatic]

4 hours ago, seabass said:

you should also know your magnesium levels

Last Mg reading was 1260. I just dropped that column as it seemed to be in proper proportion to my Ca.

[seabass]

1 minute ago, phinatic said:

Yeah. It's "0" on my kit, but I don't have a low end test kit. Same goes for Nitrate, but I know it's in there based on my feeding macro growth. I keep cutting back the macro and it keeps getting bigger 🙂

The algae might be more efficient at utilizing inorganic nutrients in your tank, so monitoring algae growth might not provide you with a full or accurate picture of what's available to your corals.  Yes, a low range kit will provide you with a better metric as to what might be available to your corals (and other beneficial photosynthetic life).

 

Food will provide input of phosphate, so even when it's undetectable, that doesn't mean there isn't a regular supply of it.  But in some cases, certain organisms might use it before others are able.  Same with nitrogen, even with undetectable levels of ammonia, nitrite, and nitrate, having fish in your tank means there is a constant source of nitrogen.

 

But I know that nutrients aren't your primary concern.

 

8 minutes ago, phinatic said:

Last Mg reading was 1260. I just dropped that column as it seemed to be in proper proportion to my Ca.

1260 should be adequate; but it's slightly below ocean levels.  Since you are dosing alkalinity, I'd probably dose magnesium up to at least 1300ppm.  However, I can't say that this is causing any loss of alkalinity or not.

[ReefGoat]

https://reef.diesyst.com/chemcalc/chemcalc.html
 

this calculator really helped me a lot when I first started dosing in my tank when the water changes were no longer keeping up. 
 

it’s way better than trying to decipher and do math with the instructions on the bottle. 
 

apologies if what brand you use isn’t available on the drop down list. Give it a look though

[seabass]

Here's an online conversion for alkalinity:

https://www.hamzasreef.com/Contents/Calculators/AlkConversion.php

 

So 10 ml adds:

• 0.5 meg/L or
• 1.4 dKH or
• 25 ppm

to every 15 gallons of water.

 

 

[mcarroll]

I think you'd see (ie naked eye) a change in growth.  And that may be coming.

 

But there are other demands for alk, such as photosynthesis (in anything).

 

More light would increase that demand immediately.  This is why you see folks get the instruction not to mess with their lights once they are set up – it affects the corals immediately, and not without cost to the corals.

 

Another part of the cost to the corals in addition to higher alk demand is in the form of higher demand for nutrient resources.  

 

We keeps tabs on dissolved nutrients by monitoring nitrate and phosphate.  

 

Yours are both apparently registering 0.00 ppm.

 

Corals are unreliable eaters in general, and not all corals put equal emphasis on eating.

 

If you haven'e read them already, I'd recommend these resources:

Nutrient Dynamics of Coral Reefs series:  https://reefkeeping.com/issues/2006-08/cj/index.php

Reef Food series: http://www.reefkeeping.com/issues/2002-07/eb/index.php

 

I would ease up on nutrient removal – and I agree on not using algae as your bellwether.  Algae have much better access to dissolved nutrients than corals, in general.  

 

So ease up on water changes, filters running, et al.  If you aren't already feeding your fish as much as you are comfortable feeding, then increase those feedings.  As a last resort, you can dose liquid nutrients if it seems like corals aren't doing well and you can't get the test numbers to budge for N and P.

 

2¢

[phinatic]

32 minutes ago, mcarroll said:

More light would increase that demand immediately.  This is why you see folks get the instruction not to mess with their lights once they are set up – it affects the corals immediately, and not without cost to the corals.

This was my thought as well. It was noticeable the next day. I decided to go ahead and make the change now before these frags are permanently fixed to the rocks. They are just in a frag rack at the moment. I wanted to end up with something closer to the Saxby model, so I was going to have a change at some point.

 

34 minutes ago, mcarroll said:

So ease up on water changes,

Already trying this. Welcome change and haven't change for 2 weeks now. :)

 

35 minutes ago, mcarroll said:

feeding your fish as much as you are comfortable feeding

Almost at the max. I added some more hermits to pick up the excess and just add more bio-load.

 

I also had a thought that the newly excess organics, from addition feeding, could be soaking up the alkalinity and then it is getting removed via skimming. I am still leaning toward the light though.

[mcarroll]

23 hours ago, phinatic said:

Almost at the max. I added some more hermits to pick up the excess and just add more bio-load.

I could be wrong, but there's an implication in there that flow could be better to keep food in circulation longer.  

 

Hermits are OK, but obviously feeding is about the fish and corals.

 

It takes really good flow to maximize the time that the food is adrift.  

 

More time = more chances for a food item to be eaten by a target organism instead of food getting caught in the sanded or scavenged, etc.

 

23 hours ago, phinatic said:

I also had a thought that the newly excess organics, from addition feeding, could be soaking up the alkalinity and then it is getting removed via skimming. I am still leaning toward the light though.

Hm.  Detritus is considered an alkalinity source (eg) when consumed by corals...so I don't think it would also be considered a source of demand.

 

Has your skimmer been acting different lately?

[phinatic]

9 hours ago, mcarroll said:

flow could be better

Flow is actually great. Had to turn it down recently. I have a 13.5 G tank with a 300 gph return pump and a 2000 gph Nero 3. I have the return set at 33% and the Nero goes from 15-40% throughout the day. The flake and frozen foods eventually get caught in my macro algae. Needed some cleaners to get in there and go get it. My clownfish won't pick food out of there. The pellets sink very quickly and move around the tank bouncing off the sand until the crabs get them. I am trying to keep them acquainted with flake/pellets for when I have to use my auto-feeder.

 

9 hours ago, mcarroll said:

Has your skimmer been acting different lately?

Not really. Possibly getting a little more skim. Was emptying once a day, now about every 18 hours.

 

I have continued testing every day and it does look like I may be "stabilizing". Looks like my alkalinity rises day-over-day when I dosed 10ml, dropped when I dosed 5ml, and stayed the same when I split the difference at 7ml. So it looks like my system is using 7ml. I also haven't had to dose my Ca/Mg/Sr mix as the calcium hasn't moved in the last few days.

 

	Temperature	Salinity	pH	Alkalinity	Ammonia	Nitrite	Nitrate	Phosphate	Calcium
Target	TRUE	TRUE	TRUE	TRUE	TRUE	TRUE	TRUE	TRUE	TRUE
Current	79.000	1.026	8.100	143.000	0.000	0.000	0.000	0.000	380.000
6/7/2023	79.000		8.100	143.000	0.000				380.000	Alkalinity 5ml
6/6/2023	79.000		8.100	152.000	0.000		0.000	0.000	380.000	Alkalinity 5 ml
6/5/2023	79.000		8.100	134.000					380.000	Alkalinity 10 ml
6/4/2023	79.000		8.100	125.000					400.000	Alkalinity 10 ml
6/3/2023	79.000		8.200	125.000					380.000	Alkalinity 7 ml
6/2/2023	79.000			152.000					370.000	3-ion 7 ml
6/1/2023	79.000			143.000			0.000	0.000	390.000	Alkalinity 5 ml
5/31/2023	79.000	1.026	8.100	152.000					400.000	3-ion 5 ml
5/30/2023	79.000		8.000	143.000			0.000	0.000		Alkalinity 5 ml
5/29/2023	79.000		8.100	152.000	0.000	0.000	0.000	0.000	380.000	3-ion 5 ml
5/28/2023	79.000	1.027		143.000						Alkalinity 5 ml