Help with Dropping Alk

[Nath514]

I have a well established 32 gallon tank with another 10 gallons of sump. It has been up and running for 2 years. Recently my alk has started dropping and I can't seem to get it back up. Normally I try to keep it in the 8.0 range but over the last few weeks it has continued to drop and just hit 6 as measured by my hanna alk tester. Some details of the tank are below:

Tank Details

• Tank: FijiCube 32EXT
• Light: AI Prime 16HD running the BRS Profile for LPS
• Skimmer: Reef Octopus essence 130
• Water Changes: Automatic nightly change handled by stenner pump 100 series doing 5 gallons every 20 days
• Return Pump: Octo varios 2 at level 2
• Powerhead: Nero 5 Running at 30% random
• Fish: 1 clown, 1 chromis, 1 dwarf angel
• Coral: Softies and LPS
• Cleanup: Mix of snails and hermit crabs
• Sump: FijiCube 20
  • First stage: is a klir 4
  • Second stage: 20 marine pure balls
  • Third stage: Skimmer compartment + Oxydator A running 6% with one reactor
  • Fourth stage: Sera Siporax
  • Fifth stage: return section
• Auto Top Off: AutoAqua ATO
• Dosing: Tropic Marin All for Reef daily ~6ml
• ALK: ~6.0
• Feeding: 2 times weekly rods frozen, 1-2 times weekly flake / pellet food
• Feeding Coral: 3 times weekly Reef Energy AB

I have tried increasing the dosing of All For Reef and adding some additional 5 gallon water changes but the alk just keeps heading down and many of my Acans are starting to look pretty shrunken with skeleton showing. Please help me to figure out what is consuming all the ALK and how to reverse the drop.

Thanks,
Nathan

 

[vetteguy53081]

What test kit are you using to check alk?
May be false reading

 

[Nath514]

Here is a current tank shot.

 

[Nath514]

What test kit are you using to check alk?
May be false reading

This is the tester I use: https://www.bulkreefsupply.com/alkalinity-colorimeter-hi755-hanna-checker-hc-marine-water.html

 

[vetteguy53081]

This is the tester I use: https://www.bulkreefsupply.com/alkalinity-colorimeter-hi755-hanna-checker-hc-marine-water.html

I trust this one
Something is absorbing at high rate and likely stony coral
Before adding any alk, take a water sample to a trusted LFS and have them test for you to see what readings they come up with and to compare with yours

 

[Ancient Mariner]

I find it difficult to raise alk just with a 2 part Ca/buffer at low levels. (My tank was bottoming out to dKH 4-5 as it was maturing.) I assume that’ll be true for All For Reef. I’d add a pure buffer to get alk to your target, then increase your maintenance Ca/alk product dosing as you follow alk levels on a daily basis. Alk consumption might be from increased coral or coralline algae uptake, which would be a good thing!

Nice tank!

 

[mdb_talon]

I would definitely start with confirming that alk value via a different test. The hanna checker can vary dramatically based off reagent batch or if the reagent is getting old in my experience (even if well within expiration but has been open awhile)

 

[Rmckoy]

I’d start with ordering a new refill bottle of reagent .
test to confirm your low readings .

I have great success with esv b-ionic 2 part dosing

you might notice a lot of consumption if you have a lot of coralline algae on the glass .

 

[Nath514]

I’d start with ordering a new refill bottle of reagent .
test to confirm your low readings .

I have great success with esv b-ionic 2 part dosing

you might notice a lot of consumption if you have a lot of coralline algae on the glass .

I have a new bottle of reagent coming and will see what that shows. Not much coraline has ever grown in my tank.

 

[Rmckoy]

I have a new bottle of reagent coming and will see what that shows. Not much coraline has ever grown in my tank.

I’ve noticed if you don’t shake the bottle of reagent every time prior to use the last 30% always gives significantly lower results
Seams weird but that’s what I noticed

 

[MrDLHughesY]

Have you checked your Mag ?

 

[Nath514]

Have you checked your Mag ?

Just measured it using a Salifert test and it came out to 1300

 

[Nath514]

I’ve noticed if you don’t shake the bottle of reagent every time prior to use the last 30% always gives significantly lower results
Seams weird but that’s what I noticed

Just tried the ALK again after some vigorous shaking and it dropped down to 5.6 so hopefully the reagent is just bad and the new bottle will yield some higher numbers.

 

[JMetaxas]

I like the Hanna Alk tester but there’s been times when the reagent goes awry. Now, I always double test with reagents from different lots. I feel much more confident that way. It only takes another minute.

 

[Nath514]

Received the new reagent today and tested the ALK. Now showing 9.6 so looks like it was just old reagent causing the low readings. So my corals not looking great is probably from the ALK being quite high ( I dropped the dossing recently so my alk was probably over 10 ). I have reduced my dosing back to where it was historically and will monitor as I bring it back down to 8.2 ish. Thank you all for the advice I should have tested new reagent earlier.

 

[homer1475]

Also just a reminder.....

The vials are 30ml, but you should only use the stated 25 tests(they give a little extra, and most tests kits do). The last bit does get old, and gives weird readings.

I mark my bottles every time I use them and only use 25 tests, then throw away the excess. I have much more consistent readings bottle to bottle regardless of what the lot numbers are.

 

[Nath514]

Also just a reminder.....

The vials are 30ml, but you should only use the stated 25 tests(they give a little extra, and most tests kits do). The last bit does get old, and gives weird readings.

I mark my bottles every time I use them and only use 25 tests, then throw away the excess. I have much more consistent readings bottle to bottle regardless of what the lot numbers are.

Thanks for the heads up. I only test once every 1-2 weeks so a bottle tends to last me longer than it probably should. Going fowards I will make sure to keep fresher reagent on hand and not use the dregs.