Alk Dropping , can't figure out why.

[Oggiewok]

Good Afternoon everyone.

I've had a RSR 250g2 up and running for around a month now, upgraded from a 120l AIO that I had running for 5 years. Mostly its been fine, however over the last few days I've noticed some irregularities in my testing.

Nirtate - 5
Phosphate - 0.09
Amm - 0
PH - 7.8
ALk - 5.7
SG - 1.025
Temp - 25C

The alk result is what has me most curious. I've done 3 10% water change (skipped the first week) since the tank was set up, the last of which was yesterday.Currently the tank is fairly lightly stocked, with some kenya tree, mushrom and GSP that I transferred over from the old tank. Livestock wise, we have:

2x Clowns
1x Royal Gramma
2x Banggai Cardinal
1x Randayys Goby
1x Tiger Pistol
2x Narssarius Snail
2x Turbo Snail
1x Tuxedo Urchin
2x Skunk Cleaner Shrimp

I've made all the saltwater myself using Red Sea Blue Bucket which should have an alk of between 7-8, however the initial fill of 250L was done using the water from the old tank (which to be fair, I never tested for alk) and new saltwater that had been in storage in a Brute container for approximately 3 weeks. Im wondering, did the alk content of the new water "degrade" while it was in storage or do even softies use up some of the alk in the water.

Cheers for any input!

 

[Crustaceon]

The only thing I can think of would be C02 created from the livestock/Co2 in the room gradually driving down ph, and seeing depressed ph can affect dkh, that too. Randy would know more on this for sure.

 

[Randy Holmes-Farley Verified Community Expert]

Good Afternoon everyone.

I've had a RSR 250g2 up and running for around a month now, upgraded from a 120l AIO that I had running for 5 years. Mostly its been fine, however over the last few days I've noticed some irregularities in my testing.

Nirtate - 5
Phosphate - 0.09
Amm - 0
PH - 7.8
ALk - 5.7
SG - 1.025
Temp - 25C

The alk result is what has me most curious. I've done 3 10% water change (skipped the first week) since the tank was set up, the last of which was yesterday.Currently the tank is fairly lightly stocked, with some kenya tree, mushrom and GSP that I transferred over from the old tank. Livestock wise, we have:

2x Clowns
1x Royal Gramma
2x Banggai Cardinal
1x Randayys Goby
1x Tiger Pistol
2x Narssarius Snail
2x Turbo Snail
1x Tuxedo Urchin
2x Skunk Cleaner Shrimp

I've made all the saltwater myself using Red Sea Blue Bucket which should have an alk of between 7-8, however the initial fill of 250L was done using the water from the old tank (which to be fair, I never tested for alk) and new saltwater that had been in storage in a Brute container for approximately 3 weeks. Im wondering, did the alk content of the new water "degrade" while it was in storage or do even softies use up some of the alk in the water.

Cheers for any input!

The alk in new IO can decline over time as calcium carbonate precipitates, but it is also normal to need to dose alk to most reef aquaria and I’d just do that.

 

[Oggiewok]

Yeah I had planned on needing to at some stage, but was hoping it would be around when I started adding stony corals. Looks like its coming round sooner than I thought