2-Part Precipitation Problems!

[Nano_Addict]

Hello all,

 

I've been dosing 2-part in my systems for years with no issues... until recently.  The past several months my tank has gone from stable one week to crazy alkalinity and calcium fluctuations the next with notable precipitation in the substrate around the rocks and near the waterline on the glass.

 

I've done loads of research and read several articles by Randy Holmes Farley, but can't pinpoint my issue.  I've calibrated my dosing pumps, stopped dosing for several days to measure the drop in Alk (measured 1.3 dkH drop which feels high considering the tank is lightly stocked) and Ca only to restart the dosing pumps at the proper amount and have the levels continue to fall.  I've programmed the dosing pumps to ensure they don't dose at the same time and even installed a small powerhead aimed directly at the spot where the dose occurs and still no luck.  

 

My pH runs between 8.1-8.3, measurements are taken via Trident, and dosing is performed via the DOS (auto dosing is not turned on). 

 

The tank is about 40 total gallons and has significant coralline growth, but only four small(ish) LPS corals at this time.  

 

Any help would be appreciated!

[mitten_reef]

looking at your instagram, the tank is rather new.  and like you said the consumption seems high for what is in there now...

 

I recall reading that precipitation can cause some type of chain reaction - keep pulling alk out of the water - under certain condition, which may give you a false usage number.

 

to the matter at hand,

how much are you dosing?  how many times/day?  where the dosed liquids go, is there good flow?  how far apart (timing-wise) do you dose them and do they go in the same general vicinity?     

Judging by your last tank journal, you aren't too new to the whole concept of dosing, I just want to get some ideas so other might be able to chime in.

[Nano_Addict]

Thanks for the quick reply!  The tank just hit the one year mark this week actually.  The only major issue I created by mistake was back in september I WAY overdosed Ca by somehow accidentally hitting the "on" switch in the fusion dashboard.  I calculated that about 900 ml was dosed to the tank.  I performed water changes and brought the levels down until they stabilized, so I don't think this would still be an issue, but I don't know.

• How much: Currently 65 ml of Alk (Soda Ash) and Ca.  This is obviously too much, but I'm also trying to balance not killing the few corals I have with getting the alk to stabilize.
• How many times per day: The DOS is set to deliver the amount over 24 hours, currently reading 130 doses approximately 11 min apart.
• How far apart are the doses timing wise:  This is a recent change (yesterday) I modified the DOS schedule to dose the additives approximately 5 min apart.
• Where are the additives dosed: Dosed into the sump between the baffle from the skimmer chamber and the return chamber.  I thought the low flow here could be an issue so about a month ago I added a sicce micra pointed up directly at the spot where the additives hit the water.

[aclman88]

6 minutes ago, Nano_Addict said:

How far apart are the doses timing wise:  This is a recent change (yesterday) I modified the DOS schedule to dose the additives approximately 5 min apart.

What was it at before?

 

Do you know your magnesium levels?

 

Do you do water changes and if so, how often?  Lastly, are you using a complete 2 -part with magnesium or trace elemnts, or is it just the soda ash and calcium?

 

Too low mg can result in precipitation.

[Nano_Addict]

Previously they were dosing at the same time, however as I mentioned I have a powerhead directed at that spot.  Additionally, the precipitation is a recent (the last two weeks) change.  I've had them dosing at the same time for probably the past two months.

 

Water changes are usually every two weeks.  I try to match fresh saltwater with the tank's parameters as close as possible.  I'm using BRS 2-part with the Balling Part C added.

 

Here's a graph of the mag levels.  There's a lot of noise in this chart, but as you can see it's averaging 1350 which is what I've been aiming for.

 

[Nano_Addict]

Just wanted to follow up on this issue.  It seems like the problem was an elevated pH and dosing soda ash for corrections rather than sodium bicarbonate.  The soda ash caused a pH spike which might have been what started the precipitation event. Since I was running a CO2 scrubber the pH stayed elevated and the precipitation continued.

 

In order to break the cycle I gave the tank a three day break from all dosing.  Now I'm slowly raising the Alk back to around 9dkh using bicarb and planning to switch back over to soda ash for daily dosing.