RO membranes

[danelle]

hey guys this may be a stupid question, but I just bought an RO system it is a coralife 50gpd system from Dr. Foster and Smith, and it is slow slow slow. Which makes me wish I had gone with the 100gpd, the question I have is the only difference between the 50gpd and the 100gpd the membrane? If I put a 100gpd membrane in would it make it faster?

 

[bang guy]

Originally Posted by Danelle
http:///forum/post/2757261
hey guys this may be a stupid question, but I just bought an RO system it is a coralife 50gpd system from Dr. Foster and Smith, and it is slow slow slow. Which makes me wish I had gone with the 100gpd, the question I have is the only difference between the 50gpd and the 100gpd the membrane? If I put a 100gpd membrane in would it make it faster?

My experience is a bit outdated so things may have improced over the years. When I used a 100gpd membrane is was really bad. The TDS out of the membrane was about 50. I switched to a 75 and it dropped to 12.
Hopefully someone with more recent experience can confirm or deny my experience.
As a result, I would personally choose not to use a 100gpd membrane.
When swapping out membranes for faster or slower you also need to change the waste restrictor.

 

[jeanheckle]

I also have a coralife unit. It's really slow as well, but when only doing weekly water changes it doesn't seem to be a problem. Actually the only problem I have had is forgetting I'm running it and going downstairs to an overflow!!

 

[danelle]

Thanks I am probably just overly anxious. I need to do water changes on a 125, a 75 and my 24gallon aquapod. One other question. Do I need to add anything besides salt to the RO water? I have been told the salt will buffer it to where it needs to be?

 

[aquaknight]

How you measured the output of the RO unit? To see if it's infact 50gpd (gallons/day). It's very possible that the incoming water is below recommended pressure (varies per unit, but I believe common is 60psi? Contact your manufacture). You might have to look into booster pump.
That said, yea, 50gpd is actually quite slow, about 2 gallons an hour. Many people who buy RO/ RO/DI units will also invest in some type of water storage, anything from a brute trashcan, to a 500gal water tank. Bang Guy is correct, the lower flow rates have a higher rejection rate, meaning more water goes down in the drain, and 'purier' water comes out. If you only are using an RO membrane, and not an addtional DI filter, 50gpd is the way to go.

 

[jeanheckle]

Originally Posted by Danelle
http:///forum/post/2757274
Thanks I am probably just overly anxious. I need to do water changes on a 125, a 75 and my 24gallon aquapod. One other question. Do I need to add anything besides salt to the RO water? I have been told the salt will buffer it to where it needs to be?
If you buy a quality salt it will have everything you need in it.

 

[danelle]

I have been using instant ocean salt. It seems to be okay, but what would be a good salt mix for a reef tank? I have had some trouble keeping my Ca up. Thanks for all the help.

 

[bang guy]

Originally Posted by Danelle
http:///forum/post/2757365
I have been using instant ocean salt. It seems to be okay, but what would be a good salt mix for a reef tank? I have had some trouble keeping my Ca up. Thanks for all the help.
IO is fine IMO. Reef Crystals is the same salt with a little bit more Calcium chloride and Bicarbonate added.

 

[mr.m]

To just put 100 gal membranes in wont work you have tho change the flow
control too . thers one for 25 gph 50 gph 100 gph and up.
Mark

 

[jeanheckle]

I use reef crystals and rarely have to add calcium and I do have alot of corals. And I have never had to add any trace elements.

 

[danelle]

Thanks for all the help. I think that I will just stick with the 50gpd. system, and the next time I buy salt I will try Reef Crystals to help with my Ca.

 

[bang guy]

Don't ignore Alkalinity.