help! Chemistry awry

[Susan Lott]

I bought a 90 gal corner tank about 2 weeks ago. It was a fish only tank containing 6 big fish. We sold 4 of the fish, because we want to convert this to a reef tank. The tank had been previously set up for about 3 years. When we moved the tank we brought all 90 gals of water with us. We have added 5- 10 lbs only of live rock. We have since done water changes every 4 days or so using R/O water.
We have added bicarb of soda for the ph and Kh. The nitrates keep spiking , the ph is all over the place. (Better since adding bicarb).
Today the readings are: nitates 80, nitrites 0, amonia .2, phos. 1.5, ph. 8.3, spec. grav. 1.020.
Should we add more live rock to help stabilize the system or would that be detrimental? What's going on? I thought the tank would be seasoned by now or did the move stir things up?
Doing a water change as I write. Heeeelp:lol:

[Sugar Magnolia]

Was the rock you added fully cured?

[Susan Lott]

Yes, the rock was fully cured. I forgot to add that we also have brown algae, and slimey green algae on the rock and glass.

[dugg]

Just a suggestion, you need to test your water that you are using to do changes before adding it to the tank, both before and after adding the salt. Some lower level ro/di systems do a poor job of removing nitrate. I recently had a simular issue and found my nitrates to be coming from the salt i was using.

Also what type of filter system are you using? Fish only type filter systems are no good for reef conditions.

[Reefmedic79]

Did you re-use the sandbed?
If so you stirred up all the nutrient that were trapped in it before the move.
What brand test kits are you using?
When were you testing pH? Same time of the day each time?
I'm going to guess that your ammo readings may be a false possitive or a difficult to read chart. pH fluctuates on it's own throughout the day. Testing in the morning will always show lower levels than in the evening before the lights go out. with that in mind, stop dosing the bicarbonate. The constant water changes to lower the nitrate should maintain the needed levels for the time being.

Gravity should be 1.024-026 for a reef tank.

[Susan Lott]

Yes, we did reuse the sand bed. The filter is a tide pool with sump, the skimmer an excaliber venturi (200 gals).
I'm wondering about the R/O unit(Aqua Baracuda 100 GPD). It's almost 3 years old and the filters have never been changed. I don't have a meter for it.
The R/O water reads 0 for nitrates.
The test kit is called saltwater master kit from Aquarium pharmiceuticals. I also have Sera Kupfer test kits.

[dugg]

The nitrate test will work for salt or fresh with the same kit.

[bertoni]

An ammonia level of 0.2 might not hurt very many animals, but some Amquel Plus might be a good temporary safety net.

This article might be worth reading:

http://reefkeeping.com/issues/2004-05/rhf/index.htm

I would replace the carbon stage of the RO-DI filter right away, and most likely the sediment and DI filters as well, if present. A TDS meter would be useful to help test the final output water, and the clean water output from the RO membrane, before it goes through the DI, to check whether the membrane is still good.

[Susan Lott]

Thanks for all the help. That was a fabulous article Jonathon. It answered a lot of questions.

[Spuds725]

Originally posted by Susan Lott
It's almost 3 years old and the filters have never been changed.

I imagine they are due to be changed-- I don't recall how long a RO membrane should last, but the pre and post filters should be changed at least once per year (IMO)