RO water and Phosphate

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ellisz

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Joined
Sep 8, 2003
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Indiana USA
With all the talk of cyano outbreaks, I have noticed that my red slime problem seems to be getting worse too. I siphon the stuff and it is back the next day. I have tried the many tips and such with feedings, water flow, etc. but never actually purchased a PO4 test kit.

I bought one at the LFS today. It is made by aquarium Pharm but it is all they had. I am getting a reading of .5 in the tank and also in my RO/DI water! I tested the water in my holding container and right from the hose itself. Can I do a membrane flush to fix this? Now that I think about it, since I have been making my own water, the cyano has really seemed to get a good foothold on my tank!

What can I do here?

BTW, I have the 100 gpd system from Aquasafe.

Thanks
 
It sounds like your DI resins are spent and need to be replace. The RO membrane doesn't affect Phosphates....it's the DI cartridge that does.
 
Personally I would run some phosphate remover for a little while, and keep syphoning. Just do this for a wek or so as patience is sometimes the key.

I'm not sure about the RO/DI filters ablity to remover Phos from the water, but you only need a very small amout to fuel algae.

John
 
I have a similar problem. I have a 2 stage RO unit. I just added a 3rd stage, a deionizer. It brought my source water PO4 from.25 down to nearly 0.
Just a though, cost me $50 but if it fixes the problem it will be worth it. I have tried everything else.
 
I am running seachem phosguard - have been for about a week. My DI cartridge is only about a month old. Should not be spent, really. I have some spares so I could give it a shot.

I read that quarryshark had a phosphate issue and he added a DI cartridge to his RO unit and it took care of it.

If I swap out the DI cartridge do you have to run water through it before using it?
 
Nope....However, before replacing resins that are only a month old, verify that your test kit is reading properly.
 
verify that your test kit is reading properly
LOL, not sure how to do that other than order a different kit :) Maybe the LFS can test for PO4. I'll have to see tomorrow.
 
Good luck Ellis. Keep me posted. I'm interested to see how it turns out. I will keep you posted as well. This is one of those pain is the backsides.
 
Any RO experts know if the DI filter is what removes the phosphates? I have a final carbon stage that is for taste. I do use this even though I don't need to. This would not cause any issues would it?

I am going to try and take some water in to a LFS today but I don't know what kit they use. Usually Aquarium Pharm. Could I get some distilled water from the grocery and test that? Would that be a good enough test to see if the test kit I have is accurate?
 
I tested my RO vs my tap water vs my system water to see if there is a different. There was a big difference.
 
that would work but I would like to test something that is 0 and is supposed to be 0 as well.

My wife keeps asking when the tank is going to take care of it self and not need all this testing :lol:
 
ellisz said:
that would work but I would like to test something that is 0 and is supposed to be 0 as well.

My wife keeps asking when the tank is going to take care of it self and not need all this testing :lol:

Agree, Its just a way to illustrate the difference. It is revealing. I took a sample to my lfs to compare.

Ya, my wife is ready to convert my tank into a planter. :roll:
 
ellisz said:
Any RO experts know if the DI filter is what removes the phosphates? I have a final carbon stage that is for taste. I do use this even though I don't need to. This would not cause any issues would it?

It most certainly can. All living things contain Phosphates. Trees were once living so therefore the activated Carbon contains Phosphates. The manufacturers of GAC are now using acid to wash as much ash as possible out of the activated Carbon and that is a great help as the Phosphate level in Carbon has decreased substantially in recent years. However, it is not completely gone. That's why I recommend that people soak their Carbon in RO/DI water for several days before putting it into their tank. The RO/DI water acts as a magnet and sucks the Phosphate out of the carbon. If your final stage Carbon filter is AFTER your DI cartridge, then this is what you might be experiencing.

One way to find out would be to take the carbon out of the last stage...make some RO/DI water without the carbon and test that. BTW...the Phosphate leaching that occurs with Carbon is highest when the Carbon is brand new.
 
Thanks. I have meant to take the post DI carbon off but did not think it would matter. It will be off tonight for some testing.

I added the RO and the MH setup about the same time so it is hard to say if the more intense light is taking the small PO4 and making it grow like gang busters. I hope it is just the post carbon. That would be the easiest to fix.
 
Well, the LFS was not help. They tested my tank water and got .25 which I thought was ok. Sort of validated my test. Then I had them test my CA and Alk just for the heck of it. The said my CA was 600 and my alk was 1.0-1.5(on the bottom he said). This is a load of you know what. I tested the water sample I took to them and gat CA of 385 and Alk of 2.5 meg/L. I wanted to get a sample of their RO water to test but I got annoyed :(

I tested some distilled water last night and got the same .5 PO4 reading. Should distilled water have a PO4 reading?

The LFS basically told me my RO/DI was sub-par and that I should have got a spectra pure like they sell. They also could not believe I don't dose iodine and strontium...

oh well...
 
First off....never dose Sr unless you have a test kit. The same thing goes for Iodine because too much Iodine will kill your entire tank.

I cannot comment on their tests because I don't know their test kits, methodologies, etc.

Distilled water can contain Phosphates. I don't know if you test kit is right nor wrong. However, a test with RO/DI water will tell you.
 
I don't dose. They thought it was odd that I don't. The test kit they were using was a Hagen master kit.

Is there retail water that I can test to verify the PO4 test on my RO/DI water?
 
Not really, most retail water is only distilled and/or run through a RO process. Drinking water is not usually run through the DI process.

Even though I'm in St. Louis, I have several friends in your local reef club. http://www.indmas.org/ I would ask them if anyone nearby has some RO/DI water you can test with or borrow a TDS meter.
 
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