33 Gallon Reef

[Frogger]

I really do not think that removing Chaeto from your tank would have any impact on the nitrates and phosphates.

How often are you testing you phosphates and nitrates and what kits are you using and have they expired?

I believe the main thing that can cause a spike is fish, coral, large snail has recently died/ disappeared in your tank.

Your corals use nitrates, phosphates as does coraline algae, and a decline in their growth can lead to an increase in the nutrients in your tank.

I have found that the best way to tell how your hard corals/ coraline algae are doing is to monitor your alkalinity usage. If your alkalinity usage is dropping, basically your measured alkalinity is increasing you could have an issue.

[Sidius]

You are likely right (same thing another experienced reefing friend recently told me). It was just an observation as it seemed to happen almost over night after removing the chaeto. I've done an extra water change this week to bring them back down to 10ppm now (I typically do a 4 gallon change every Sunday). I'm testing every other day with Salifert test kits purchased from J&L about 6 months ago.

What prompted me to start testing was basically within a day or two of removing the chaeto, I had a green film algae growing on all my glass to the point I was having to scrape it a couple times per day (I'm pretty anal about clean glass but it was very noticeable). Prior to that I hadn't had to scrape the glass in weeks. It very likely was be caused by a trochus snail that died and it was just a coincidence. I'm still trying to get an accurate count. I will remember the tip about the Alkalinity usage. I have just ordered a Red Sea Reef Foundation test kit and will track that as well.

[Synthesis]

Just an observation here, but you said that you have 20 snails in a 33 gallon tank. Snails need a constant food source. They also produce waste. Eventually your system becomes mature enough that you may not be producing enough algae as a food source and they will slowly starve. You can watch many videos online about the issues surrounding many "clean up crew" packs being huge overkill and most just dying off slowly which will cause spikes in nutrients.

To put your 20 snails in perspective, I have 8 snails (4 varieties) in a 25 gallon tank along with 4 small hermits and a single emerald crab. The tank is really clean for the most part and the snails are all very happy.

Keep a close eye on all 20 snails.