Curing cement/oyster shell rocks

headdr · Apr 5, 2018

So I am setting up a new larger tank 8ft penninsula 300 or so gallon. I didn't want to spend a lot on rock. I made some cement rock with some portland cement and oystershells. Lot of fun really. I have cured the rock in the tank for about 6 months or so. Long story. I am finally about to start putting in some livestock. For some reason I cured the rock with saltwater. Does anyone know if the curing process gives off toxins or if it just causes the ph to spike? Id prefer to put the money into frags as opposed to buying more salt. My parameters have been stable so I threw in a few test critters from my other tank. The 8 blue leg crabs are doing fine but the damsel and snail are MIA after a week. Do I need to dump water and start over?

Monkeynaut · Apr 6, 2018

Sounds like a big tank. I would personally try with another fish before I dumped the water.
I also would run good carbon for a few days/week before I tried the fish. You will inevitably run carbon on a tank that size anyway?

H@rry · Apr 6, 2018

I have read in the past that oyster shell is pretty high in phosphates. I've never tried it so I can't say for sure.

headdr · Apr 6, 2018

Phosphates are low, my parameters are in range. Nitrates and ammonia almost non existant. Alk is around 4 dk, I am dosing a teaspoon of arm and hammer (sodium carbonate) every night now to get it up. Ph is stable trying not to spike it. Magnesium is about half what it should be 700 instead of 1350. I did not think that would phase a damsel. Blue leg crabs are loving it not sure why....

headdr · Apr 6, 2018

In hind sight it was a bad idea to sacrifice the damsel without having the alkalinity right. Just wanted to get things moving. Have had this tank for almost 2 yrs with nothing in it. I am starting to run carbon this weekend. Gonna give that a week or 2.

Monkeynaut · Apr 6, 2018

Dustin Head said:
Nitrates and ammonia almost non existant.

Ammonia is 0 right?
My impression is that almost 0 could still be too high for Ammonia. I thought all ammonia should be converted before it can show up on a test in a completely cycled tank.

beaslbob · Apr 10, 2018

I have heard the cement does not cure under salt water. But you seem to have disproven that LOL.

Using FW you were supposed to do water changes until the PH lowers. that was the sign it was cured.

My .02

eric.battani · Apr 10, 2018

I've cured it in saltwater before but it raises calicum really high and ph.

headdr · Apr 10, 2018

Yup. Calcium is really high and my magnesium is low. Been dosing baking soda to build up alk. I think this has kept the ph down. What do you do when calcium is high?

eric.battani · Apr 11, 2018

Not much other than water changes or adding some hardy calcium loving corals but water changes are usually the best way. Or let it participate out but you would have to read up on what to add to achieve that

headdr · Apr 12, 2018

Been dosing baking soda with ro water and my alk is not going up. Should I pull my filter socks? They are clogging up and tuning brown quickly. Could they be pulling out the sodium bicarbonate as soon as I pour it in?

mikey5290 · Apr 12, 2018

You will need to get the magnesium back to normal levels, or you won’t be able to balance the calcium and alkalinity.

Flippers4pups · Apr 12, 2018

Agreed the about magnesium dosing.

Here's a good read on alkalinity supplement dosing:

http://reefkeeping.com/issues/2006-02/rhf/index.php

I use Randy's part 2 for alkalinity to keep my alkalinity where I want it. I make it into solution using his recipe.
Then I dose it using this calculator:

http://reef.diesyst.com/chemcalc/chemcalc.html

headdr · Apr 13, 2018

So the red box on this post say the manufacturer of mag flakes no longer recommend product for reefs. would u still recommend using deicer from home store? Any other good cost effective sources for Magnesium chloride hexahyrate?

headdr · Apr 13, 2018

So the red box on this post say the manufacturer of mag flakes no longer recommend product for reefs. would u still recommend using deicer from home store? Any other good cost effective sources for Magnesium chloride hexahyrate?

Flippers4pups · Apr 13, 2018

Dustin Head said:
So the red box on this post say the manufacturer of mag flakes no longer recommend product for reefs. would u still recommend using deicer from home store? Any other good cost effective sources for Magnesium chloride hexahyrate?

I go to BRS for magnesium.

beaslbob · Apr 13, 2018

I use magnesium hexa chloride from brentag in Huntsville. It like $30 for a 50 pound bag. They ship in it from a warehouse in Tennessee but don't charge for shipping.

And I still have some if you wanna try.

my .02

chipmunkofdoom2 · Apr 13, 2018

Something is very wrong with the chemistry in this tank. There's no way your magnesium should be 700 ppm. Alkalinity is also way, way off at 4 dKh. What is your salinity? How are you measuring salinity? What test kits are you using for alkalinity and magnesium? What is your calcium?

Personally, I would correct salinity if it's off (I suspect it is), then I would do a large water change. I know it's a big system, but Instant Ocean is only $50 for a 200 gallon box. You'd rather spend your money on corals, I understand, but this hobby is more about keeping water than it is about keeping fish or corals. You're not going to get anywhere by cutting corners with water quality.

beaslbob · Apr 13, 2018

I and an old member (8ball) both had magnesium at 700-800ppm prior to dosing. In my case it took literally pounds (~5 or so) of magnesium chloride to get it up to 1300-2400ppm. Old 55g tank.

So that value is realizable.

my .02