Alk and Calcium consumption seem suspiciously high

[Phistergosh]

I have a red sea reefer 250 so its 65g of water volume (not my nano in the build thread). My alk consumption seems to be climbing consistently. I test, set my dosing pumps, then retest after two days and adjust the dosing pumps as needed. I have been dosing 78ml per day of Cal and Alk (BRS soda ash and BRC calcium). I just tested again after 2 days and my consumption is up to 90ml of each! Could this consumption really be legit or is something else going on? I have a little of everything as far as corals go. They are all still pretty small frags from live sales. My tank has been running for 7 full months so its still pretty new. I had a mixed reef tank for years but just got back into the hobby.

When I started keeping records in July, I was adding 20ml a day of each. Im all the way up to 90ml. It seems like the more I add, the more is needed. Looking at what I could, it seems like 90ml a day is pretty high for a mixed reef. I have some STN on my two acro frags and a Monti which I am attributing to Alk spiking from this constant demand increase then trying to adjust back upwards.

I don't see any coralline growth on the pumps or return nozzles. I see some on my rocks (hard to tell because they were purple colored liferock from caribsea). I clean the glass (including the back) well each week so I wouldn't expect coralline to grow there. I do a weekly WC of 10 gallons religiously.


Other things to note:
I split the dosing to 12 times a day for both alk and cal. They are dosed an hour apart from each other into my sump. pump is calibrated
mag is 1400 and pretty stable
maybe 50 lbs of caribsea liferock, 25 lbs of agrilive sand, a few pieces of live rock from a LFS to help seed.
I use Red Sea test kits and I use Rea sea pro coral salt. I tested my salt mix and my kits are matching what it says it should be so I feel like the kits are OK
I keep the tank at 1.0255 salinity and the refractometer is calibrated.
I keep the tank at a stable 75 degrees measured with two analog thermometers
I have 2 clowns and two small yellow tail damsels (so my fish load is pretty small). full CuC of snails, hermits, 2 emerald crabs
My nitrates are low at 4 to 5 ppm. phosphates are always near zero so I have been dosing phosphates and using Coral AB+
No Skimmer because my nutrients are already too low.
Filter floss that I change regularly.

 

[homer1475]

Not unheard of consumption depending on coral load? Picture of tank? Checked your sandbed to see if it's turning hard anywhere, meaning your having a precipitation event?

In comparison, I have an SPS dominant mature 85 gallon tank. I dose 110ml of alk and cal daily.

 

[Phistergosh]

Not unheard of consumption depending on coral load? Picture of tank? Checked your sandbed to see if it's turning hard anywhere, meaning your having a precipitation event?

In comparison, I have an SPS dominant mature 85 gallon tank. I dose 110ml of alk and cal daily.

My sandbed was hard in a few spots. I read something randy said that it happens in new tanks and not to worry. I thought he said nobody knew why it happened.

The hard spots happened a few times total though so I don't even think that would account for the constantly increasing demand

 

[homer1475]

No thats not supposed to happen. It can bind the sandbed a little bit(basically bind it enough it won't blow around), but it should not turn hard. Thats a precipitation event, where alk and cal are preciptating out turning the sandbed hard. The more you preciptate, the more you dose, and so on untll you start seeing snow in your tank.

Ask me how I know....

 

[Phistergosh]

The sand bed has been clumping. I crush it with my hands when I'm about to vacuum. So it's not rock hard because it's still crushable.

I guess that makes sense though. Because the demand is very high and it's not like my corals are growing extremely fast. I was aiming for 10 dkh and 430 ppm cal. Maybe I'll knock that down to 8.5 and 390 and see how things go.

I use the Red Sea Coral pro salt. The dkh on that is 12ish. I think I need to look into a different salt mix. Of course I just cracked open a new bucket last weekend.

 

[homer1475]

You can lower the ALK if you want to continue using that salt. It's a pretty simple process really. Just involves some really simple math, and a mineral acid.

If the sandbed is clumping at all, it's precipitating. Stop dosing for a couple days, retest, then dose accordingly to bring your levels up to where they should be. A couple days of slow decline in ALK and CAL will not hurt the corals, just keep in mind not to raise ALK faster then 1dkh per day as more tends to stress corals.

 

[Phistergosh]

I dropped my dosing from 90ml to 60ml. Been going like that for 24 hours. The alk is exactly the same as when I tested yesterday. That makes me think I was precipitating out the equivalent of at least 30ml a day. I'm going to let this go for a few days then reduce again and observe.

 

[Phistergosh]

Update: I dropped my alk and cal down to 40 ml a day by dropping and retesting with a attempt to hold at 8.5. When I was dosing up to 90ml a day, many corals started to decline and stn. Since backing it off, everything is coming back and growing well. I think the soda ash based all solution was causing ph swings and alk swings as it was added then precipited out.

Instead of trying to maintain a 11 dkh like my salt, I settled around 8.4.

 

[Spare time]

No thats not supposed to happen. It can bind the sandbed a little bit(basically bind it enough it won't blow around), but it should not turn hard. Thats a precipitation event, where alk and cal are preciptating out turning the sandbed hard. The more you preciptate, the more you dose, and so on untll you start seeing snow in your tank.

Ask me how I know....

I had bad precipitation at one point and I didn't realize it and now part of my sandbed is rock (forms a really cool cave actually) haha.. My diamond goby and tiger tail cucumber live in it.