Question about high KH

ben310135 · Jan 13, 2015

So I have had my tank now for about 4 or 5 months. Long story short I had an outbreak of marine velvet and my dt is now fish-less and they are in the qt. However I have some Brain coral and some inverts in the tank just waiting out the life cycle of the marine velvet. So my current setup is I have a 75g tank with a canister filter fluvial 305 with bio balls and carbon as well as a protein skimmer. I came home and noticed my Brain coral was receding bad to the point I could see the skeletal structure. Now I know these things are really touchy. But I have never seen it this bad. So I was going to do a water change and did. Cleaned everything and waited 6 hrs and did a water test. My results are below

Ph 8.4
Ammonia 0
Nitrate 0
Nitrite 0
Calcium 450
KH is 75 ppm which I know is high.

Also I have using R.O. Saltwater for all my water changes I do about 6 gallons a week. I am still learning everything so I am wondering a. what I can do if anything to lower KH as I said most things I have found say do a water change which I did. Just wondering if there are any other ideas ?

Randy Holmes-Farley · Jan 13, 2015

75 ppm calcium carbonate equivalents for alkalinity is actually very low. I recommend 125-200 ppm (7-11 dKH).

So I'd look to add baking soda if you think it is accurate.

However, I'm surprised the pH is at 8.4 with that low alk. So double check that the alk kit is working by testing some new salt water first.

ben310135 · Jan 14, 2015

So I retested today and my ph is at 8.0 alk is at 200 ppm. I have Marine buffer by seachem which will increase and maintain my ph to 8.3 I just didn't know if those will be ok with my corals I also have inverts in my tank and wanted to make sure they would be ok if I added this or if you had something else you would recommend over the Marine buffer ?

Cory · Jan 14, 2015

In my experience velvet shows itself when alkalinity gets low (below 125ppm or 7dkh). You should be testing for alkalinity only, don't worry about ph. Ph is mostly a concern if it drops below 7.8. But if you maintain alkalinity at 125-200ppm CaCo3 then ph should never get below 7.8.

ben310135 · Jan 14, 2015

Ok so if alk is 200 ppm and the other parameters look good why is my brain coral looking so ****** (receded)

Randy Holmes-Farley · Jan 14, 2015

200 ppm is plenty high. You do not want it higher.

The Seachem product will not give you pH 8.3, but it will boost alkalinity (which you do not want).

It also isn't a good choice for a reef tank as it has too much borate in it for our purposes.

Randy Holmes-Farley · Jan 14, 2015

I don't know why the coral is suffering, but open brain corals often do not survive long term.

Cory · Jan 14, 2015

ben310135 said:
Ok so if alk is 200 ppm and the other parameters look good why is my brain coral looking so ****** (receded)

It's possible your phosphates are too high. Phosphates stunt calcium from being deposited. But I agree with Randy too.

KoleTang · Jan 14, 2015

Cory said:
In my experience velvet shows itself when alkalinity gets low (below 125ppm or 7dkh). You should be testing for alkalinity only, don't worry about ph. Ph is mostly a concern if it drops below 7.8. But if you maintain alkalinity at 125-200ppm CaCo3 then ph should never get below 7.8.

Velvet and alkalinity have no relationship to my knowledge. What are you referencing here?

Cory · Jan 14, 2015

KoleTang said:
Velvet and alkalinity have no relationship to my knowledge. What are you referencing here?

I'm quoting my experience. I have no scientific evidence. However place any organism in an environment that causes stress, weather it's chemical or territorial it tends to perpetuate disease by lowering their immune system. People are the same way, you get fired at a job and mysteriously get sick. Some kids call you names then you get sick. With millions of bacteria present in every corner I'm surpirised we are not already dead, but some how we manage to live with them without dying.

KoleTang · Jan 14, 2015

Cory said:
I'm quoting my experience. I have no scientific evidence. However place any organism in an environment that causes stress, weather it's chemical or territorial it tends to perpetuate disease by lowering their immune system. People are the same way, you get fired at a job and mysteriously get sick. Some kids call you names then you get sick.

Bicarbonate levels don't affect fish much at all. A change in bicarbonate would not be enough to cause a fish to get sick. Perhaps the low alk is in relationship to low pH, which could stress out the fish.

While it is true that stressed fish are more susceptible to sickness, that doesn't necessarily mean they are more susceptible to velvet (parasite) unless their slime coat has been weakened. Even a healthy fish can get velvet. That is why quarantine is key.

With millions of bacteria present in every corner I'm surpirised we are not already dead, but some how we manage to live with them without dying.

That's what an immune system is for.

ben310135 · Jan 19, 2015

What should my phosphates be ?

Cory said:
It's possible your phosphates are too high. Phosphates stunt calcium from being deposited. But I agree with Randy too.

Randy Holmes-Farley · Jan 19, 2015

Different reefers with different corals strive for different phosphate levels, but 0.02 or 0.03 ppm are reasonable target levels for most aquaria.

Cory · Jan 19, 2015

phosphates are best kept under .03ppm. If a test kit even reads a tiny amount you've got too much. But phosphate also fluxes, which people usually don't consider, and that flux can cause algae growth and calcium from not being deposited.

Ah I see Randy beat me too it!