Cycling New Tank - Advice

Etto · Dec 3, 2021

I started my new tank (78 gal / 108 gal total) about 4-5 weeks ago with 2 clown fish from my old nano tank and Dr. Tim's. My ammonia is a faint green, it's more than yellow but not quite 0.25. Nitrites and Nitrates are both max on the card (Red Sea test kits). I've read different things about Nitrites and whether they matter or not. Should I wait for them to go to zero?

I've been watching lots of videos (BRS, etc). Some are confusing because they range from 6yrs old to current and it seems lots has changed in that time. Not the basics but enough to make things confusing.

At present I have no filter socks, the skimmer is off and I've done no water changes.

Is it time to do a water change and add the socks and skimmer? How much of a water change?

I have a lawnmower Blenny, Yellow Tang and Tomini Tang in quarantine tank for the past 3 weeks. When should I start adding them.

Thanks for any advice

Quietman · Dec 4, 2021

So...ammonia sounds fine. Your test is measuring total ammonia (NH4 + NH3) and we're only concerned about free ammonia (NH3). NH3 only makes up approx 1/20th the value of total ammonia at normal reef tank pH. That puts it at <.012ppm and a far below toxic range of 0.1 ppm.

Nitrites aren't toxic in seawater as chloride is used more readily in the biologic processes that intake nitrate. Freshwater doesn't have 19000 ppm chloride so it's toxic for freshwater fish. Not sure about pegging high on nitrites with 2 clowns in 75 gallon - seems unlikely so recheck test and exp date on kits.

Since you're at top range of nitrates - you'll want to do a series of water changes to get those down to 5-10 ppm or so.

Once you have nitrates down start adding in your new fish. You could add now, but why stress them to high nitrates.

Get your nutrient export systems working (skimmer, mechanical filtration, biopellets, carbon dosing) whatever you're using as reef tanks are as much about maintaining quality of water as keeping fish/corals.

Good luck!

tharbin · Dec 4, 2021

I agree. Start doing water changes but your Nitrate reading is really more for reference value until your Nitrites come down. You can't get accurate Nitrate readings while you have Nitrites with most hobby test kits.

Basically, you are still building up your bacteria levels. I would go very easy on any stocking changes util your Nitrites come down. It is not toxic but it is an indicator that the tank is still immature.