High alkalinity with low water change alkalinity

[Mattrg02]

So here is a true puzzle for everyone.

My tank alkalinity seems to go up despite my water change alkalinity staying low.

My dkh usually is around 9. Today I woke up to find a millepora with a few tips with stn. I test dkh and find its now at 10.

My water change water is 7, yes, 7!

How can dkh stay high with water change water low? I'm using neomarine salt and have been for a few months. My dkh never drops despite doing 30% water changes weekly.

Also, on the weekends, I run my skimmer super wet and pour several cups of fresh salt water into the tank to maintain salinity.

What's going on here?About to lose a millepora to this, I assume.

 

[abecker]

The alk issue sounds like a good question over on the reef chemistry board. Have you double checked the salinity to make sure that isn't rising with the alk?

 

[Randy Holmes-Farley Verified Community Expert]

I'll move it.

 

[Mattrg02]

The alk issue sounds like a good question over on the reef chemistry board. Have you double checked the salinity to make sure that isn't rising with the alk?

Yes, I measure salinity several times a day. Stays solid at 1.025

 

[Randy Holmes-Farley Verified Community Expert]

Alkalinity can only rise if it is added to the water somehow.

Ways can include:

1. Topping off with tap water that has alkalinity in it.
2. Release from artificial rock that uses cement (including frag plugs)
3. The consumption in the aquarium of nitrate (so nitrate is declining due to uptake)
4. Rise in salinity (as mentioned above)
5. Addition of something else that contained alkalinity. Do you add anything aside from foods?
6. A batch of Neomarine for water changes that is higher than you thought due to inhomogeneity within a bucket (settling and separation of the contents)
7. Mismeasurement of the alkalinity (not that rare)

 

[Mattrg02]

Alkalinity can only rise if it is added to the water somehow.

Ways can include:

1. Topping off with tap water that has alkalinity in it.
2. Release from artificial rock that uses cement (including frag plugs)
3. The consumption in the aquarium of nitrate (so nitrate is declining due to uptake)
4. Rise in salinity (as mentioned above)
5. Addition of something else that contained alkalinity. Do you add anything aside from foods?
6. A batch of Neomarine for water changes that is higher than you thought due to inhomogeneity within a bucket (settling and separation of the contents)
7. Mismeasurement of the alkalinity (not that rare)

Top off is rodi water, same as what mixed with the neomarine.

Got a few cement frag plugs, not many. No artificial rock.

Nitrate has gone down to "yellowish" on my API test. I added some potassium nitrate to bring it up.

I don't dose anything aside from microbacter 7

Neomarine is measured at 7dkh after mixing.

 

[Randy Holmes-Farley Verified Community Expert]

Adding nitrate via potassium nitrate and having it be consumed will boost alkalinity, so it might be that, or the frag plugs.

Consumption of 10 ppm nitrate will boost alkalinity by 0.45 dKH.

 

[Mattrg02]

Adding nitrate via potassium nitrate and having it be consumed will boost alkalinity, so it might be that, or the frag plugs.

Consumption of 10 ppm nitrate will boost alkalinity by 0.45 dKH.

Dang. Maybe that's it. It's been creeping up? How do I lower it? Large water change?

 

[Randy Holmes-Farley Verified Community Expert]

Water changes won't be very efficient unless you decrease the alk in the new water, which you can do using muriatic acid from hardware store. There are many threads on that.

 

[Vividgraphx]

what salt are you using?

 

[Mattrg02]

what salt are you using?

Neomarine.

Already low in dkh.

What would everyone say to using a large and cheap sps colony to eat up alkalinity?

 

[Randy Holmes-Farley Verified Community Expert]

It's far easier and quicker to use an acid in the water change water (or directly to the tank, if you want, but be more careful of that) to lower it and offset the additions from the plugs.

 

[Mattrg02]

Won't adding acid also drop pH? My pH is chronically low at around 7.8 despite many efforts to raise it.

I've tried opening windows and adding a slimmer. Neither do a dang thing to raise it. This is the same through out 3 different salt brands.

pH starts out okay in the PWC water. After the PWC, the pH just stays solid at 7.8

 

[Vividgraphx]

sounds like ph is a problem. what is the temp usually at?

 

[Mattrg02]

sounds like ph is a problem. what is the temp usually at?

77F

 

[Vividgraphx]

does it fluctuate? im pretty sure ph will directly effect your alk. I might be wrong. Regardless 7.8 seems kind of low. I usually dose 8.4 cause mine tends to drop as well. I have noticed every week and a half right around the time of my water change my alk is lower and ph has dropped. A pH of 7 is considered to be "neutral", neither acid or alkaline, while pH above 7 is alkaline or "base", and below 7 is acidic. I'd say 7.8 is pushing it for a reef. In a fish only under 8 works but reefs are too touchy. I was having many many issues with alk,calc. I switched to red sea coral pro with bi weekly water changes and my problems went away. I still have to watch the ph though.

 

[Randy Holmes-Farley Verified Community Expert]

Won't adding acid also drop pH? My pH is chronically low at around 7.8 despite many efforts to raise it.

I've tried opening windows and adding a slimmer. Neither do a dang thing to raise it. This is the same through out 3 different salt brands.

pH starts out okay in the PWC water. After the PWC, the pH just stays solid at 7.8

Adding muriatic acid will temporarily lower the pH, and that is why I prefer to do it on water change water, as you can aerate it after adding the acid to blow off the excess CO2 and raise the pH back. Maybe drop it to 3 dKH. A 10% change would then lower alk from, say 11 dKH to 10.2 dKH.

 

[Mattrg02]

It's stable at 7.8, from what I can tell. That's why I haven't bothered with any buffers. I'd like to avoid the swings caused by them. I'm guessing my c02 levels are just too high in my apartment. From what I understand, 7.8 is okay if stable. Only issue is that adding acid should drop pH...

Any other way to drop alkalinity? Looks like a cheapo sps colony is the only hope.

 

[Randy Holmes-Farley Verified Community Expert]

does it fluctuate? im pretty sure ph will directly effect your alk. .

Alkalinity and CO2 together control pH, not the other way around.

 

[Mattrg02]

Adding muriatic acid will temporarily lower the pH, and that is why I prefer to do it on water change water, as you can aerate it after adding the acid to blow off the excess CO2 and raise the pH back. Maybe drop it to 3 dKH. A 10% change would then lower alk from, say 11 dKH to 10.2 dKH.

How do I keep it from rising? Seems pwc drop it to around 8dkh, but then it creeps back up. Funny huh?