Water hardness, brackish aquarium

bitbot

AC Members
Nov 10, 2008
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Sydney, Australia
Hi, would value some input on this subject, as I am new to brackish aquaria:
I have started up a small (60l) aquarium to keep some bumblebee gobies.
I have added some seawater (2 litres; from the sea).
The GH is now testing at about 25*

Is this normal?
Even though it is only about 4% seawater, ie low-end brackish, the GH is already high for this species, from what I've read.

Or have I missed something?
 
Is your water source already hard?

It isn't anything to worry about though, since BBGs prefer hard water anyways.
 
Using sea water can cause a lot of problems in an aquarium (disease or parasites), it is advisable to mix your own. You will need a hydrometer or refractometer to measure the salinity of the water.
You could try using peat in your filter to bring the hardness of the water down or if you are feeling rich you could use RO water.
 
Using sea water can cause a lot of problems in an aquarium (disease or parasites), it is advisable to mix your own. You will need a hydrometer or refractometer to measure the salinity of the water.
You could try using peat in your filter to bring the hardness of the water down or if you are feeling rich you could use RO water.

Thanks for your reply.
I'd like to give using real seawater a try.
I've bought a hydrometer today, the tank is 1.002 (tap water here is 1).
What I'd really like to know, because I can't find this information anywhere, is what is the (normal) hardness of hardness of 100% seawater, and is 25 a normal reading for a 4% seawater mix?
 
Only suggestion I can think of in regards to seawater is to adress the above mentioned parasites and desease. I've read that if you want to use sea water make sure where you collect it from is not near a sewage etc runoff. Also to collect the water and let it sit in a bucket with a lid for 2 weeks so everything will die off and should then be ok to use, filter out debris if you wish. I read this from a "how to set up a marine tank" published in the 80's so i don't know if new things have come up.
 
Many folks who live near the ocean use NSW for their tanks. Hardness is not an issue with these fish. You are fine.
 
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