Sea lab 28 experiment

[Randy Holmes-Farley Verified Community Expert]

Dinos are always in the conversation, haha! More importantly, my thoughts are that sometimes observed reactions in the reef aquarium have nothing to do with the changes we make. An example, maybe, is your comment with regards to this product: “The person who saw alk decline was probably from normal alk consumption”

I don’t disagree with the commonality of coincidences in reefing and how folks may often mistakenly blame the most recent thing they did.

 

[VintageReefer]

I have begun my Sea-Lab 28 testing and here are my results so far:

Test Setup:
75g mixed reef, heavily (over packed maybe) packed with corals, lps dominant, 11 acro frags ranging from 1 to 3”

80g water volume factoring for sump, sand, rock etc

Water changes
- not performed on this system

Dosing
- alkalinity is auto tested and auto dosed every 4 hours using kh guardian. Dosing solution is sodium bicarbonate mixture
- khguardian is set to auto dose to 8.25 dkh

- manganese is added daily, 1.0ml

- no calcium supplementation being performed.

Sea-Lab 28 observations
- testing period 4/14/25 to 4/25/25
4/14/25
- tested calcium - 352
- added 1 sea-chem 28 cube to sump return chamber. Flow is constant speed, no critters to interfere with block. Return pump pulls consistent current around the cube 24/7

4/20/25
- first cube is 80-90% depleted
- left cube in place and added new cube

4/25/25
- tested calcium - 397
- original cube is gone
- second cube approx 40% left

Over 11 day period, no impact to alkalinity

Nothing out of the ordinary here. The kh guardian tests every 4 hours, if dkh is below 8.25, it doses to bring it to 8.25 or close to it. Over the next 4 hours dkh drops, and then is brought back up. Dkh typically drops to a low of 8.1 and is brought up to approx 8.3 or occasionally 8.4.

So far 2 cubes over a 11 day period has provided calcium for my systems consumption + added 45 ppm.

In future I will wait for one cube to fully dissolve before adding another, that might prevent the slight increase

I have noticed no change in ph since starting these cubes and no negative effects. I think long term use needs to have the timing nailed down for when to add a new cube, and also an understanding of how much calcium a cube provides

 

[Garf]

I have begun my Sea-Lab 28 testing and here are my results so far:

Test Setup:
75g mixed reef, heavily (over packed maybe) packed with corals, lps dominant, 11 acro frags ranging from 1 to 3”

80g water volume factoring for sump, sand, rock etc

Water changes
- not performed on this system

Dosing
- alkalinity is auto tested and auto dosed every 4 hours using kh guardian. Dosing solution is sodium bicarbonate mixture
- khguardian is set to auto dose to 8.25 dkh

- manganese is added daily, 1.0ml

- no calcium supplementation being performed.

Sea-Lab 28 observations
- testing period 4/14/25 to 4/25/25
4/14/25
- tested calcium - 352
- added 1 sea-chem 28 cube to sump return chamber. Flow is constant speed, no critters to interfere with block. Return pump pulls consistent current around the cube 24/7

4/20/25
- first cube is 80-90% depleted
- left cube in place and added new cube

4/25/25
- tested calcium - 397
- original cube is gone
- second cube approx 40% left

Over 11 day period, no impact to alkalinity

Nothing out of the ordinary here. The kh guardian tests every 4 hours, if dkh is below 8.25, it doses to bring it to 8.25 or close to it. Over the next 4 hours dkh drops, and then is brought back up. Dkh typically drops to a low of 8.1 and is brought up to approx 8.3 or occasionally 8.4.

So far 2 cubes over a 11 day period has provided calcium for my systems consumption + added 45 ppm.

In future I will wait for one cube to fully dissolve before adding another, that might prevent the slight increase

I have noticed no change in ph since starting these cubes and no negative effects. I think long term use needs to have the timing nailed down for when to add a new cube, and also an understanding of how much calcium a cube provides

So, prior to this test, when was the last time you added calcium? 350ish was very low, and you noticed no problems?

 

[Randy Holmes-Farley Verified Community Expert]

Do you know how much alk the guardian added? That would help understand how much calcium was being consumed and so how much calcium was actually released.

One obvious question is whether there is a useful advantage over a one time dose of calcium some other way.

 

[VintageReefer]

I was behind on calcium dosing and additionally I forgot to record my last calcium addition. Several weeks. I haven’t noticed any problems

Then I intentionally did not add any calcium products while I awaited the sealab 28 to arrive, to minimize risk of overdosing. I didn’t know what to expect from one cube.

So, prior to this test, when was the last time you added calcium? 350ish was very low, and you noticed no problems?

 

[VintageReefer]

Do you know how much alk the guardian added? That would help understand how much calcium was being consumed and so how much calcium was actually released.

One obvious question is whether there is a useful advantage over a one time dose of calcium some other way.

563 ml of alkalinity solution comprised of 65g baking soda / 1000 ml rodi

 

[Randy Holmes-Farley Verified Community Expert]

563 ml of alkalinity solution comprised of 65g baking soda / 1000 ml rodi

That amount of alk would have consumed 35 grams of calcium. That’s 115 ppm in your system.

Thus, the Sealab was adding calcium at about 40% faster than the rate of consumption to give that calcium rise.

 

[VintageReefer]

Ok. Soooo. It DOES add calcium lol
I can see how people end up in the 500’s without proper testing and planning

And if I used roughly 1.5 cubes in 10 days then maybe I need to add 1 cube every 10 days for approx 34% reduction

 

[ValidParadox]

Ok. Soooo. It DOES add calcium lol
I can see how people end up in the 500’s without proper testing and planning

And if I used roughly 1.5 cubes in 10 days then maybe I need to add 1 cube every 10 days for approx 34% reduction

Did you end up continuing to use it? I'm giving it a go tonight.

I think a concern I have about testing calcium here is that most calcium tests aren't accurate +/- 50ppm.

 

[VintageReefer]

Did you end up continuing to use it? I'm giving it a go tonight.

I think a concern I have about testing calcium here is that most calcium tests aren't accurate +/- 50ppm.

I continue to use it successfully. 1 cube per 8 days roughly

 

[Minifoot77]

I continue to use it successfully. 1 cube per 8 days roughly

You done an icp with it yet

 

[VintageReefer]

You done an icp with it yet

My coral are my icp

I will add, I manually add manganese daily for the gonis and turf scrubber algae.

 

[ValidParadox]

Update: The product's instructions say to use 2-3 nuggets per 10 gallons. I used one for my 5.

I tested alk and pH about 3 hours after dropping it in for the first time. I dropped it in a low flow corner.

My alk went from 7.4 to 7.0 (Hanna Checker)

My pH went from ~8.2 to ~8.0 (API Kit)

I did not test my calcium before, but when I tested my calcium now, it was over max range (Hanna Checker= 600+)

I tested around 10pm and 1am. pH drop was expected as I'm in the blues night time. My lighting schedule is as shown:

I'm doing a water change now to combat the calcium reading.

 

[Randy Holmes-Farley Verified Community Expert]

Maybe time to give up on a poor product. :)

 

[ValidParadox]

Maybe time to give up on a poor product. :)

I'm glad it works in some capacity for some people, unfortunately it wasn't for me.

 

[VintageReefer]

Look Update: The product's instructions say to use 2-3 nuggets per 10 gallons. I used one for my 5.

I tested alk and pH about 3 hours after dropping it in for the first time. I dropped it in a low flow corner.

My alk went from 7.4 to 7.0 (Hanna Checker)

My pH went from ~8.2 to ~8.0 (API Kit)

I did not test my calcium before, but when I tested my calcium now, it was over max range (Hanna Checker= 600+)

I tested around 10pm and 1am. pH drop was expected as I'm in the blues night time. My lighting schedule is as shown:

I'm doing a water change now to combat the calcium reading.

You are overdosing clearly. Your nuggets look half size as mine, and mine is one cube per 80gallons. You need to test and figure out how much to use

If your tank is 5 gallons I would stick to water changes. It’s a small volume of water and minor changes / inputs can cause very noticeable outcomes

You need to ignore the product claim and then use the instructions as a start point. Every tank is different.

My alk went from 7.4 to 7.0 (Hanna Checker)

On Hanna checker, with its level of accuracy these readings are technically identical. Accuracy is +/- .3 dkh.
Let’s say the water is actually 7.2dkh. The Hanna meter can report back anything from 6.9 to 7.5 dkh, and be considered an acceptable test result.

My pH went from ~8.2 to ~8.0 (API Kit)

I don’t trust these tests at all, but let’s assume it’s accurate and true. No harm will come from this, and I ran my reef for over a decade and never crossed 8.0 ph. I was typically 7.8-7.9. Check my build thread if you want to see the coral growth and health

I did not test my calcium before, but when I tested my calcium now, it was over max range (Hanna Checker= 600+)

Ok well this is good to know. Testing after the cube and not before isn’t that helpful, but it is still useful

Your calcium is high. The cube is mainly calcium supplement product. You’ve added too much, or added at a time it was not needed

Suggests reset with large water change
Test all parameters
Wait a week and test them all again
See how much calcium was consumed in a week
add 1/4 of your cube and measure ca in 24 hours-see if it increases or decreases
Adjust and figure out the proper dosage based on calcium consumption, and test results

 

[VintageReefer]

If you want to make it work, I believe you can. But it will take some trial and error, adapting, and education on how it works, just like many other products out there

If it means anything, my larger cubes…the instructions say both 2-3 cubes at once, and also 1 cube at a time for a tank roughly my size. I had to figure out my dosage also