New Doser / ALK Spike to 14+ dKH - What to do?

[underwood]

Last week, I probably jumped the gun by setting up my new GHL Doser 2 on a Sunday, right before I left town on Monday for a business trip. While configuring everything, I tested the pump flow for both Ca and Alk 5+ times each and thought I had everything "dialed in", but I obviously did not give myself time to closely monitor everything for a couple days before leaving town. While I was out of town, I asked my wife each day to look at the tank and tell me if anything looked out of the ordinary, but was told every night that things looked good.

I get home tonight - the tank looks fine - but I decided to test the Alk anyway and it tested at 15+ dKH (Salifert). I re-tested with a brand new test kit, but same result. Meanwhile, SPS / LPS look great and the fish are acting fine. A couple SPS actually had big growth spurts while I was gone. I did notice that the Alk was lower than the Ca in the side by side dosing container (were at the same level on Sun), and I had configured the Ca to dose ~2.5x more per day than Alk. Either the flow on the Alk pump adjusted after I left or the something funky is going on with the doser.

To further complicate matters, due to recent weather, I only had enough saltwater mixed to do about a 12% water change. Now the water is testing at 14 dKH. Besides the water change, here is what I have done:
- I turned off the doser.
- Adjusted LED settings to turn down the white lighting from ~60% to 40% (under the impression high ALK + high light = burned coral... please correct me if that is not accurate)
- Dosed enough Ca so it was roughly 1:1 equivalent for while I was gone.

Tomorrow is supposed to get into the 40s so I can hopefully run my RO/DI unit and make some more water to do gradual water changes.

If everything otherwise looks good, what would you do? From what I have read, it sometimes takes a couple days for the effects to become apparent in the corals. Should I take normal polyp extension / etc as a good sign for now?

 

[Rob.D]

From my experience, if an alk spike is causing stress the corals will show quickly. I would shut the dosing pump down and test daily to see if the ALk is falling on it's own. If the numbers hold steady, I would try to continue water changes but this might not help depending on the alk levels of newly mixed water. If water changes will not help, you will just have to wait it out. The good part of waiting it out, is that testing daily will give you a good reference to how much alk is being consumed.

 

[UK_Pete]

One thing you could do is make up as much new water as you can and drop the alk of it to zero with muratic acid, then you could use this 'very low alk' stuff to have much more significant effect on your tank than normal 'high alk' new water. How fast you should drop your alk for coral safety I don't know though. BTW after adding the muratic acid you need to aerate the new water to blow off CO2 as Randy described in this forum about a month or two ago (you can search his posts probably). If you tell your target alk, system volume and how much water you can mix up now, someone will be able to calculate how much this will work / muratic acid quantities for you.

 

[FarmerTy]

We did the exact same thing with a friend's tank. We added muriatic acid to lower the alk of the new saltwater and aerated it overnight... then completed water changes with the new saltwater. It helped lower his alk quickly but most of his corals were dead already by that point so lowering the alk quickly was not an issue.

If you use Randy's calculations, just a heads up but when we mimicked the calculations, it was off and we had to add more muriatic acid than calculated. Not sure if we calculated wrong or there were external factors such as period of aeration following the acid addition that threw it off but I thought it worth mentioning.

 

[UK_Pete]

Its easily possible the muratic acid was not the strength Randy specified - often hardware store acid and such is not the exact strength they claim. I can't remember what acid Randy specified, but if it was 35% ish, much of the hardware store stuff is 20%, so you would need a fair bit more. You can even dose into your tank but it would have to be really slowly, because it causes dramatic pH lowering. So if you can watch your pH accurately you can do that. Try like 1 drop and wait for 10 mins for a pH reading, continue like that etc.

 

[Skynyrd Fish]

Bring it down slowly.

 

[Randy Holmes-Farley]

We did the exact same thing with a friend's tank. We added muriatic acid to lower the alk of the new saltwater and aerated it overnight... then completed water changes with the new saltwater. It helped lower his alk quickly but most of his corals were dead already by that point so lowering the alk quickly was not an issue.

If you use Randy's calculations, just a heads up but when we mimicked the calculations, it was off and we had to add more muriatic acid than calculated. Not sure if we calculated wrong or there were external factors such as period of aeration following the acid addition that threw it off but I thought it worth mentioning.

Some types of muriatic acid sold are more dilute. Any type that claims low fumes accomplishes that by dilution, vouching that as a benefit.

 

[FarmerTy]

Well that probably explains it then. Thanks guys!

 

[underwood]

Thanks everyone for the advice. The tank still looks normal. Alk has dropped down to 12.4 range (w/o further water changes from last night).

I am running RO/DI to mix up more saltwater. Right now, I am inclined to just do 10% water changes each day and otherwise let it naturally Alk decline to avoid too big of a swing.

If I notice coral health deteriorating at all then I will go the muriatic acid route. In any case, I am filing away the muriatic acid info in the back of my head in case a similar issue arises at some point in the future.

 

[mike007]

I would quit dosing until levels come down where you want them. You don't want to any drastic changes at this point to stress corals anymore than what has been done. With dosing pumps you need to figure out what your tank Is consuming each day so you can adjust accordingly. Get your levels where you want then and go 3 days without dosing and retest and divide results by 3. Then go to the reef calculator and it will tell you how much to dose each day to maintain parameters.

 

[underwood]

I would quit dosing until levels come down where you want them. You don't want to any drastic changes at this point to stress corals anymore than what has been done. With dosing pumps you need to figure out what your tank Is consuming each day so you can adjust accordingly. Get your levels where you want then and go 3 days without dosing and retest and divide results by 3. Then go to the reef calculator and it will tell you how much to dose each day to maintain parameters.

Mike - I still have the doser turned off. If you read my original post, my issue wasn't that I did not know how much to dose. The issue was with the calibration of the pump on the doser (I tested 5-6 times and thought I had it calibrated, but something must have changed). Then the issue was compounded by me being out of town for 4 days.

 

[NanaReefer]

Plus you already stated you turned off the doser and are letting the ALK drop on its own-lol.

 

[Randy Holmes-Farley]

I personally wouldn't bother with the daily 10% changes.

 

[underwood]

Much belated, but I thought I would provide a post mortem in case someone else eventually finds this thread while troubleshooting a similar issue.

I ended up letting the ALK drop naturally over a few days. I did not end up losing any corals. The colors on my "very pink" stylo dulled a bit, but that was about the extent of it.

The doser calibration issues were resolved after I upgraded to the latest firmware and re-calibrated everything. Everything has been working like clockwork the past three months.

As an aside, I've used the muriatic acid tip a couple times to lower the alkalinity of freshly mixed saltwater when I have had batches that ran high.

 

[AquamanE]

good info guys, thanks for sharing.

 

[Randy Holmes-Farley]

Sounds good.

I'm glad it worked out well.