Startup transients


New member
Hello. Long time reader, first time poster.

I thought it might be interesting to post some details about the startup transients in my new reef tank. I've obtained lots of good information from Reef Central, and I have discovered that this reef chemistry stuff really works as advertised! Thanks for all your help so far!

Tank details:
75 ga RR AGA with 20 ga sump - approximately 80 gallons of net water volume
Rio 2100 return pump
2 Koralia power heads
Marineland 100 skimmer
90 lbs live rock
live sand bed 0" - 2" in depth
IO Reef Crystals salt mix
BRS RO/DI system - 0 TDS out of the DI filter
2 - 175 W 14K metal halide bulbs - on 7 hrs
4 - 48" T5 fluorescents - on 11 hrs
LED moonlights - on randomly
16 ga water changes every 2 weeks

Current livestock:
2 ocellaris clowns
1 royal gramma
1 yellow tang
3 green chromis
6 astrea snails
3 nassarius snails
2 peppermint shrimp
2 scarlet cleaner shrimp
1 blood red fire shrimp
about a dozen coral frags - lps, a few easy sps, and one zoa

(all added gradually over the past 3 months)

The tank was cycled and ready to go on Feb. 6. On Feb. 7, I added the first livestock - the CUC, clowns, and royal gramma. Below is a plot of various tank chemistry parameters since that date.


Some observations and other notes:

1) I was amazed at how rapidly the nitrates rose after the initial installation of livestock. I probably overfed, but clearly the denitrifying capacity of the tank took a bit of time to get established.

2) On March 3 I added a fist-sized clump of Chaetomorpha algae and some live rock rubble to the refugium section of the sump. You can clearly see the start of a much faster time constant for nitrate reduction at this point. It was amazing to me how much this helped. Since that time, the refugium has started producing a good amount of pods as well - an added advantage.

3) On about March 10 I began to have an outbreak of red cyanobacteria on the substrate and live rock, as well as in the refugium. I've been interested in using solid carbon dosing in the tank, so at this point, I decided to give IO natural nitrate reducer a try, to see if this was a good idea. I also began dosing some Special Blend bacteria to help out with bacterial diversification. Since then the cyano has almost disappeared - just a few light spots on the substrate. Because solid carbon dosing seems to give positive results for my system, when I've exhausted my supply of IO NNR, I plan to switch to a biopellet reactor.

4) Since I had added a few corals by this time, on March 18 I started using saturated kalkwasser as part of my top-off regimen. I top off manually with a mixture of kalk and DI in the morning, and with pure DI in the evening. As the corals grow (and I add more), I will gradually move over to pure kalk in the top-off (and an ATO). I was out of town for one week in April, and during that time the top-off was pure DI - hence the dip in Ca and alk for that one test period.

5) I still have a bit of cyano on my substrate. Because the nitrates have been at 0 ppm steadily for about a month now, I'm assuming I still have some phosphates in the system (I haven't bothered to measure phosphates, because the test kits have such poor resolution at low concentrations). So two weeks ago, on April 16, I added Rowaphos in a bag to a high-flow part of the sump. Since that time, the last few bits of cyano have been gradually disappearing. Yahoo!

6) One thing I have been a bit surprised about is the performance of my skimmer. Reviews of this model are decidedly mixed. It did take me a bit of tweaking at the beginning, but the skimmer definitely pulls out lots of nasty gunk, and seems to keep up with the bioload. So far, it seems okay. I'll keep an eye on it, though :spin3:

At this point, I have been very pleased with how the tank looks. The corals are growing nicely, and have good color. The fish all get along well with no bickering. I did have some recession on one polyp of my branching frogspawn at the time the nitrate concentration was dropping rapidly, but spot feeding with some cyclopeeze has encouraged the frogspawn polyp to regrow nicely. My SPS (Monti cap and Seriatopora) are growing quite rapidly. This weekend I'm going to add a few frags of some harder to care for SPS - we'll see how it goes.

Clearly my biggest challenge going forward with this tank is to balance the nutrient reduction with the needs of the LPS corals and the chaeto in the fuge (chaeto hasn't been growing nearly as much since the solid carbon dosing began). I'm looking forward to it!

Thanks for all the great information on Reef Central! This place is a goldmine for a rookie like me.

Last edited:

Randy Holmes-Farley

Reef Chemist
Premium Member
<img src="/images/welcome.gif" width="500" height="62"><br><b><i><big><big>To Reef Central</b></i></big></big>

I'm glad it going well and thanks for posting that graph. :)

FWIW, it's hard to distinguish the pH and sg. :D