Sharp drop in alk

[Paul Cooke]

Hi all

After dosing 3 part component from aquaforest for a few weeks I have seen a stable dkh of 7.1 to 7.3... however over the last two days without changing the dosing I saw a sharp drop to 6.5 dkh...I can't explain it.

I have 6-7 colonies of sps in the tank all doing well. They are newly added within the last month.

Could it be now they are settled in the tank, they have simply started to consume more alk at a sharp rate?

I changed two more things in the two day period of the drop in dkh. I moved my dosing tubes from the main display to the sump (tested and working fine) plus I added 7g of alk buffer in an attempt to raise the dkh by around .5 as per AF calculator.

Can anyone help explain? I am using Hanna test kits which have been reliable so far...

Thanks

 

[CMO]

Hi all

After dosing 3 part component from aquaforest for a few weeks I have seen a stable dkh of 7.1 to 7.3... however over the last two days without changing the dosing I saw a sharp drop to 6.5 dkh...I can't explain it.

I have 6-7 colonies of sps in the tank all doing well. They are newly added within the last month.

Could it be now they are settled in the tank, they have simply started to consume more alk at a sharp rate?

I changed two more things in the two day period of the drop in dkh. I moved my dosing tubes from the main display to the sump (tested and working fine) plus I added 7g of alk buffer in an attempt to raise the dkh by around .5 as per AF calculator.

Can anyone help explain? I am using Hanna test kits which have been reliable so far...

Thanks

Lots of things can cause this, especially early on in a tank's life <1 year old. A few things that could cause a drop like this would be a change in nutrient levels (NO3 and PO4 especially if bringing up from very low near zero levels or dropping PO4 rapidly with fresh GFO), change in PH levels (higher PH will cause greater consumption), precipitation (various factors), testing error (should test at exact same time each day) and faster growth from corals settling in at different rates.

Have you changed GFO by chance? This can really sharply drop alk. If that's not it, what is your dosing schedule like and did you test at the same time of the day?

 

[Paul Cooke]

Good tips thanks!
The tank is 14 months old, but only recently have I been adding sps. Currently there are no adverse effects to corals and they look happy, good extension etc. Hopefully the drop was just a blip.

Having raised alk to 8 last night, 10 hours later it tests the same with the same dosing measures.

I changed out gfo and carbon 2 weeks ago, as part of a clockwork schedule.

I am thinking that when I moved the dosing lines, I could have created air/a shiphon or something which impacted dosing...I have now re routed pipes back to main display.

Will test twice daily over Thai weekend to monitor.

Not looking forward to going on holiday soon! Very nervous re sps!

 

[SewerynAquaforest]

Glad that all came back on track
I agree with advices above. You should always test your parameters because consumption of your tank will change. Biomass of corals will grow and they will need more. Sometimes they will stop (reduce) consuming because of numerous reasons, then you should be ready to correct dosings. It's like that ...
Please remember in situation when suddenly your kh will drop (double check tests ) to not rise kh immediately. Do it slowly in few days.
Happy reefing