RO/DI testing

**bubbletip** · 09-14-2006, 12:01 AM

Has anyone tested their RO/DI water from their home units? I finally broke down and bought a Spectrapure Max Cap RO/DI - 90gpd. No more extra trips to the LFS wasting that other valuable fluid(gasoline). Whew-hew! So I thought. I tested the water after set up (I let 5 gallons go before collecting this first round).

Phosphate .5ppm

Tap water Phosphate - between 2ppm - so it obviously removed some of the phosphate.

Nitrate - 0

I also tested the RO/DI water from the store and it tested at .5ppm but a bit lighter of a color than what I produced at home.

Has anyone tested and found the same result? I am not sure what to think, knowing introducing any phosphates to our tanks is not a good idea.

**Amphibious** · 09-14-2006, 12:07 AM

Some hobbyist level test kits are notoriously inaccutrate. What brand are you using?

**bubbletip** · 09-14-2006, 12:16 AM

I hear you "Amp" but if it is noticeable that there is a change in the color for both the LFS water, the home water, and definitely with the tap water, it appears to have phosphate. I am using Aquarium Pharmaceuticals phosphate kit. Maybe I should try a Salifert as all the rest of my kits are Salifert and they obviously test accurately for the majority. So I take it you test "0" for your RO/DI water?

**Amphibious** · 09-14-2006, 12:57 AM

Yes. I have some AP kits but my phosphate is Salifert.

**PSH** · 09-14-2006, 01:08 AM

My test is the same as yours with the AP tests. What is your TDS? I am about to replace all the filters and retest. I hope that I get better readings.

**bubbletip** · 09-14-2006, 01:13 AM

Wow PSH, lets hope both of our test kits are reading phosphate when they shouldn't. My TDS from the tap is about 145 and 1 after the membrane(so I am getting 99% rejection). My TDS out of the 2 DI cartridges are both 0. They are brand new cartridges, so that is what I would expect. Now I am really curious to hear what others say. Maybe these test kits are bad or maybe many are reading slight phosphate out of their units.

**bubbletip** · 09-14-2006, 05:48 PM

I contacted Spectrapure today and they felt the test kit must be off as well. There suggestion was to test the kit using distilled water. I don't know why I did not think of that. Does anyone know where to purchase distilled water?

**Braves11** · 09-14-2006, 06:07 PM

You can buy a bottle at just about any grocery store.

**CarmieJo** · 09-14-2006, 11:14 PM

Make sure that if a lighting source for reading the test is recommended that you are reading the test under the correct lights.

**bubbletip** · 09-15-2006, 08:03 AM

Thanks for the tip Carmie. I have tried incandescent, halogen, and daylight. What light is recommended. A certain Kelvin type bulb? What phosphate kits do people use and are confident are accurate? I have yet to try Salifert, at least for phosphate.

**CarmieJo** · 09-17-2006, 06:54 PM

I think it may depend on the test kit but usually cool white fluorescent lights.

**bubbletip** · 09-18-2006, 02:22 PM

I tested the water in my tanks using the same test kit and both tanks were reading "0." I decided I would run some more water through the RO/DI and after letting go a few gallons the water was producing "0" phosphate. I guess I just needed to let it run longer. I thought 15-20 gallons was overkill when starting the membrane and blocks. I guess it just takes longer for some units. One thing is for sure, I will test product water at the beginning of each batch to make sure it is ok.