DKh is out of control - please help

[russmenard]

Greetings. I have a six month old tank that I want to add corals to eventually. Currently I only have fish. My setup is a 40 gallon breeder, Seachem 75 HOB, small Tunze skimmer, UV sterilizer, Helio 200 watt heater, and two AI Prime lights. I am in Mozambique so I don't have access to normal accessories, which I have to buy when I go home to the USA twice per year (next trip in six months). The fish and crabs I have are ones that my son and I have caught in tide pools here.

My dKH is at 15 and it seems to just stay there. I use RO water which measures .3 and I mix it with Mera salt, which has a dKH of 10 according to the packaging. Sometimes I use water from the good old Indian Ocean too when I can get to a good place to collect it.

My dKH was 15.3 (Hanna test kit). I just did a 25% water change with the RO/Mera mix and it's still 15! I'm also getting GH readings of 180 on a test strip. I don't know what the GH should be but I know the dKH is too high. My calc is 510 ppm (Red Sea test kit), magnesium is 1470 ppm (AquaForest test kit) and pH is 8.3.

I am trying to narrow down the possible causes of the high dKH. I was hoping to build my hardscape with Marco Rocks but ran out of suitcase weight and room! Instead, my friend gave me several big chunks of coral skeleton that he had (see picture). They look cool but I'm wondering if they might be contributing to the alkalinity problem. Is that possible? I can scavenge the beaches here for bits of reef rock if I need to replace the coral skeletons. What do you think? Are the coral skeletons my problem? If not, do you have any other ideas?

I really appreciate your help.

 

[exnisstech]

Just watching as I'm curious because calcium reactor media is small peices of dead coral and used to raise alk and cal. Your cal is also a little high, at least from what I'm used to. Not sure if there has to be CO2 dissolved for it to raise levels as in reactor? I'm sure someone with more knowledge will chime in.

 

[Randy Holmes-Farley Verified Community Expert]

Just watching as I'm curious because calcium reactor media is small peices of dead coral and used to raise alk and cal. Your cal is also a little high, at least from what I'm used to. Not sure if there has to be CO2 dissolved for it to raise levels as in reactor? I'm sure someone with more knowledge will chime in.

yes, it does need lower pH than about 7.7 to dissolve.

 

[Randy Holmes-Farley Verified Community Expert]

Greetings. I have a six month old tank that I want to add corals to eventually. Currently I only have fish. My setup is a 40 gallon breeder, Seachem 75 HOB, small Tunze skimmer, UV sterilizer, Helio 200 watt heater, and two AI Prime lights. I am in Mozambique so I don't have access to normal accessories, which I have to buy when I go home to the USA twice per year (next trip in six months). The fish and crabs I have are ones that my son and I have caught in tide pools here.

My dKH is at 15 and it seems to just stay there. I use RO water which measures .3 and I mix it with Mera salt, which has a dKH of 10 according to the packaging. Sometimes I use water from the good old Indian Ocean too when I can get to a good place to collect it.

My dKH was 15.3 (Hanna test kit). I just did a 25% water change with the RO/Mera mix and it's still 15! I'm also getting GH readings of 180 on a test strip. I don't know what the GH should be but I know the dKH is too high. My calc is 510 ppm (Red Sea test kit), magnesium is 1470 ppm (AquaForest test kit) and pH is 8.3.

I am trying to narrow down the possible causes of the high dKH. I was hoping to build my hardscape with Marco Rocks but ran out of suitcase weight and room! Instead, my friend gave me several big chunks of coral skeleton that he had (see picture). They look cool but I'm wondering if they might be contributing to the alkalinity problem. Is that possible? I can scavenge the beaches here for bits of reef rock if I need to replace the coral skeletons. What do you think? Are the coral skeletons my problem? If not, do you have any other ideas?

I really appreciate your help.

GH is not useful in seawater, it’s a measure of magnesium and calcium and strontium combined in a weird unit of measure.

have you been tracking alk to see it rise?

 

[Reef.]

Are you double sure you are testing the alk correctly.
You sure be 100% sure what your fresh salt mix alk is before adding it, if my tank I would correct the alk of your sea water (around 7ish) to check your test kit is working and you are doing the test correctly, then mix up a fresh salt mix at the alk you want, I would aim for 7-8 then use that for your water changes to bring the alk down.

 

[arking_mark]

Could this be a salinity issue? If your salinity is high, all your parameters will be high.