Hi all, new member here.

My tank has been running for perhaps a year now. Its a waterbox cube 20 (75l). AI Prime on 75% across most channels (except green and reds).

Amm - 0
Nitrite - 0
Nitrate - 0
Phos - 0
Temp - 27.5
Salinity - 33
Kh - 8
Ph -8.4
Cal - 450
Mag - 1350
Weekly 25lt water change with nsw

I have a small gyre pump which runs very low and a small hob Skimmer, I have a bag of purigen in the filter and a bag of carbon. stocking wise there's 4 clowns (will be moving a pair on once a pair is established), a few snails, and crabs, 1 skunk and 2 peppermint shrimp. I started everything from scratch with dry rock and sand etc

My issue is that corals just don't thrive in my tank, even "Hardy beginner corals". I have mushrooms, star polyps and Duncans and they're just not growing and other things I've tried eventually wither away.

What am I missing??

Thanks

Yea I was thinking perhaps down the same route, I recently tried to increase nitrates by increasing feeding but I saw no change, possibly because I have the purigen in there? Is there another way to increase nitrates?

What tests do you use? I would expect nitrates and phosphate to be above zero as others already said.
Would you not want salinity at 35?


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Cheers for the input guys, appreciate it.

I use api for the basics and salifert for kh, calc, mag and Phos

As far sal salinity goes, I use nsw and have some salt/ro to adjust if necessary but haven't ever needed to adjust that, just try to keep things stable.

Would the purigen be stopping any nitrate building up?

Would agree with the other posters - raise your nitrates and phos a bit and it might help. You could reomove the purigen, turn off the skimmer for a bit, feed more or add more livestock. Any could give a boost

Might also be worth lowering water changes a bit. 10% a week is fairly standard. Changing a third will also knock back your nutrient levels