recommend specific gravity

[Midland-marine]

As LU says definately remove the mussel as it was a 500yr old technique to start the cycle, we now know that the bacteria gets itself going from the salt you use to the rock you put in, pretty much everything really.

What is the NO3 (nitrate) running at, if amm and nitrite has fallen then nitrate should be falling too

Regards

[chrisn73]

Of course, the bacteria is already on the rock
Thinking back to cycling my tropical tank with a sterile set up
Nitrate has been zero all along
thanks

[little urchin]

hey!....no

marine is totally different to trops and it does take a bit of getting your head around

[chrisn73]

Ok time for an update, I have bought a refractometer, calibrated it and sg is 1.025 but calcium level of 360ppm has me concerned.
I have carried out a set of tests today; ammonia and nitrite are still zero but nitrate is now 10ppm, should this be remedied with water changes or can I expect denitrifying bacteria to establish as the tank matures? I know I'm thinking about my freshwater cycle again but assume this is the same. I now have the brown diatoms on some of the live rock, again I assume this is is normal in a new set up, I recall reading I can expect three algae cycles in a new marine tank, anyone confirm this?
Thanks

[LTD]

Algae cycles are normal and they should pass in time.

Ca of 360 is low but have you tested the mag and KH too ?

[chrisn73]

KH 10deg, I don't have a magnesium test kit

[LTD]

viewtopic.php?f=6&t=9119

You'll want to be buying a magnesium test kit ...........

[chrisn73]

Thanks test kit it is tomorrow then. What about water changes? should I address the magnesium/calcium levels first?

[Midland-marine]

It is better to do the change, let it mix for an hour or two then test and buffer/add to suit.
At least that is how i find it best in my small tank

[chrisn73]

I am mixing my saltwater now to add tomorrow, in the meantime I've carried out an Mg test on the tank and it is also low 1020ppm.

[Miggsy]

I am mixing my saltwater now to add tomorrow, in the meantime I've carried out an Mg test on the tank and it is also low 1020ppm.

1020 is actually very low .. when the freshly mixed salt is fully dissolved could you test that too please for the 3 params ( kh / cal / mag ) and post the results for us ?

What brand of salt are you currently using ?

[chrisn73]

I'm using Red Sea Coral Pro, I will post test results tomorrow.

[chrisn73]

This is the water I've mixed overnight
OK heres goes

S.G. 1.028 (tank is currently 1.024)

Mg 1170 ppm
Ca 380ppm
dKH 10

[LTD]

You'll need to bring down the SG (add more RO) and retest I think.......

[chrisn73]

Either way these levels are too low. Adding more RO will dilute the levels of Mg and Ca. I'm only changing about 10l in a 130l tank this should go some way to bringing the tank SG to 1.025