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dmatt56 09-14-2009 05:50 PM

Water Change Advice + Low Oxygen
Hello Everyone,

Well, the fun never ends. I checked my water parameters last night, and I noticed by pH dropped from the usual 8.3 to ~7.8 (not sure over what time period) I was instantly quite alarmed even though nothing seemed too bothered in the tank (soft corals, inverts, and the 9 fish). Nothing has changed, except for the fact that my temp fluctuated from 77 - 80 over the weekend due to extra body heat and lighting in the room. I had a plastic bag floating in my sump, containing a frag for a friend.

After doing research I learned that I could 1) add baking soda or 2) test the water again after making water movement - essentially oxygenating the water. Well, I basically filled and emptied a Solo cut for a half hour, and tested the water again. The pH was back to 8.3. (I initially tested the water after my return pump was shut down to clean the filter materials.)

Long story short, I think I had a problem with the gas exchange and the plastic bag in the sump limited the oxygen getting to my water. Everything appears to be normal again. Should I be worried about the temporary low pH? Is there anything I need to do?

I plan to do a partial water change. I noticed the tub I keep my fresh salt water has developed some type of algae/bacteria. It's clear and kinda slimy. Is this normal? Should I clean the container and make fresh salt water? Should I dump the container?

Any advice would be appreciated.



Pasfur 09-14-2009 09:12 PM


It is not possible to correctly answer your question without first testing for alkalinity and calcium.


dmatt56 09-14-2009 10:00 PM

It's not changed since the tank has been setup. PK remains 7-8dKH or 125.3-143.2 ppm KH and Calcium has been stable at 500 mg/l. My nitrates and phosphates are high, 40 and <1, respectively.

I'm mixing a new batch of H2O today to change tomorrow.


Pasfur 09-15-2009 05:52 AM

It sounds like you have the pH situation under control. I would continue to spot check pH over the next week or so, especially testing in the morning hours, prior to the lights coming on.

I would personally mix a new batch of saltwater. No reason to take a chance.

dmatt56 10-04-2009 07:45 PM

Good news. I did a water change and the pH has been under control since that initial scare.

My nitrates are getting high ~ 40-80 and phosphates ~1. The nitrite and ammonia are both 0. I'm wondering if my 2 month old bags of Chemi-Pure are becoming a phosphate and nitrate trap. They haven't been rinsed since I added them.

Also, when I replace the chemi-pure with fresh bags, will the quick and dramatic reduction of nitrate and phosphate shock the system? Am I better slowly reducing the nitrates?



dmatt56 10-04-2009 08:07 PM


Another question for you, the soft corals and fish ALL seem to be doing well. My yellow leather, toadstool, and other softies keep growing.

I am using the cheap Petco API test kits. Is it possible that they are not testing accurately? I would think the corals or fish would be acting odd if the elements were getting too high.


Pasfur 10-07-2009 03:35 PM

A quick reduction in phosphates and nitrates will not shock the system. This is a good thing.

I think you should invest in another Nitrate test kit to confirm your readings.

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