Phosphates in RODI water

[Kyle Sicard]

Hey all,
I've been battling green hair algae for a long time now with my 110g system. I'm in the process of gearing up for a complete tank restart where I would use muriatic acid on the rocks to eliminate the leaching of phosphates. I didn't think about it till just the other day that maybe my RO water has phosphates in it causing all my problems. I would really love the idea of not having to put all the work in to restart my tank so I decided to test the phosphates in my RODI mixing brute to see if the problem is in the RO system.

Basically I just tested the water and I got a phosphate level of 0.085ppm via a hannah checker. I also picked up the standard solution to check the accuracy of my hanna and it turns out that it reads 12ppb lower then it should, I contacted hannah and they said the sensor is porbably starting to get worn out. So my RO water is probably reading closer to 0.1-0.12ppm when you take the accuracy issue into account.

My RODI system's filters are all up to date. The carbon/sediment filter is 4.5 months old (time for a change next month). The DI resin is about 10 months old but still reading 0 TDS on the output, I think it's lasting a long time because my TDS is reading 0 before the DI resin. And the membrane is about 10-11 months old.

I think my problem with the RODI system is that I'm only pushing 30 PSI on the 75GPD unit. I thought the low PSI only meant that I would produce water much slower and it wouldn't affect the quality of the water since I was reading 0 TDS on the output. Now I'm thinking the low PSI is causing my unit not to function properly regardless that the TDS is showing 0.

Quick 2 questions:
1.) Is RODI water suppose to have some phosphates in it or should it be 0?
2.) Do you think the membrane has possibly been damaged from such a low PSI?

I'm probably going to be picking up a booster pump asap to correct the problem. I'm thinking I may be able to skip the tank restart once I fix the RODI issue. No wonder I'm having problems with hair algae if every time I do a waterchange or the ATO tops the tank off i'm just adding phosphates into the tank.

 

[jsker]

I have been battling Phosphates for months, it might be from my addition two small pieces of dry rock in June, food, I have not ideas. I have checked everything that I am doing. I have used No3 Po4 x and that help a little bit. I started running Rawa /a type of GFO and it cut my phosphates in half. I ordered a media reactor and I should get it next week and I am going run twice the amount of Rawa in the reactor and I should have my phosphates well with in range. my phosphates were running as high as .64ppm the droped to .036ppm with water changes, but made to many and drop my BIO load. Started with the Rawa and I am running .012ppm and with the reactor and careful feeding i should be running a .02 after nest week

 

[Randy Holmes-Farley Verified Community Expert]

That phosphate level in your RO/DI water is unimportant, even if it seems like a lot. Don't worry about it, whether it is real or not. Getting it to zero won't be significant to the tank.
You add more than 10-100 times as much in foods as you do using that water.

I show that here

http://www.advancedaquarist.com/2012/3/chemistry

from it:

Comparison of Food Sources of Phosphate to Other Sources
What about other sources of phosphate, like the "crappy" RO/DI water containing 0.05 ppm phosphate? A similar analysis will show it equally unimportant relative to foods.

Let's assume that the aquarist in question adds 1% of the total tank volume each day with RO/DI to replace evaporation. Simple math shows that the 0.05 ppm in the RO/DI becomes 0.0005 ppm added each day to the phosphate concentration in the aquarium. That dilution step is critical, taking a scary number like 0.05 ppm down to an almost meaningless 0.0005 ppm daily addition. Since that 0.0005 ppm is 40-600 times lower than the amount added each day in foods (Table 4), it does not seem worthy of the angst many aquarists put on such measurements. That said, tap water could have as much as 5 ppm phosphate, and that value could then become a dominating source of phosphate and would be quite problematic. Purifying tap water is important for this and many other reasons.

 

[Kyle Sicard]

I'm running 5-6 cups of GFO to keep my phosphates under 0.1ppm in a 75g DT +30g frag tank. I have horrendous algae issues with green hair algae, if I dont change the GFO out after 3 weeks it all grows back. The tank has been setup for 17 months. I'm at my wits end with this algae problem, it's getting to the point where I just want to break the tank down. This is a hobby i've been doing for a long time and I really do love it but this algae is getting ridiculous. It's requiring me to do way to much work having to constantly rip all the rock out and scrub it down only for the hair algae to grow back. I've tried all in one bio pellets and crap loads of GFO to no avail. I'm using 3-4x the amount of gfo thats recommended for my tank size and still the hair algae grows. I do feed my tank pretty well but its not like I'm just dumping food in the tank, i've cut feeding back to once a day.

My last effort at quelling this problem is soaking all the rock in muriatic acid and basically restarting the tank. I was really hoping all I had to do was fix my RO unit but it sounds like thats not the issue. I'm going to pick up a booster pump regardless.

Does anyone have suggestions for something like this?

 

[drstratton]

I'm running 5-6 cups of GFO to keep my phosphates under 0.1ppm in a 75g DT +30g frag tank. I have horrendous algae issues with green hair algae, if I dont change the GFO out after 3 weeks it all grows back. The tank has been setup for 17 months. I'm at my wits end with this algae problem, it's getting to the point where I just want to break the tank down. This is a hobby i've been doing for a long time and I really do love it but this algae is getting ridiculous. It's requiring me to do way to much work having to constantly rip all the rock out and scrub it down only for the hair algae to grow back. I've tried all in one bio pellets and crap loads of GFO to no avail. I'm using 3-4x the amount of gfo thats recommended for my tank size and still the hair algae grows. I do feed my tank pretty well but its not like I'm just dumping food in the tank, i've cut feeding back to once a day.

My last effort at quelling this problem is soaking all the rock in muriatic acid and basically restarting the tank. I was really hoping all I had to do was fix my RO unit but it sounds like thats not the issue. I'm going to pick up a booster pump regardless.

Does anyone have suggestions for something like this?

Try Phos RX! I've had great success with it, Melev uses it, you can check it out on his website. If you're serious about taking the rock out and soaking it use Lanthanum. I learned about that from Randy & Pete polyp. Here's a link to the thread where we talked about it!

https://www.reef2reef.com/threads/what-is-lanthanum.217373/

Here's is a link to a thread that Melev has on R2R about Phos Rx.

https://www.reef2reef.com/threads/tired-of-phosphates.129798/

And a video about getting rid of GHA.