[davemartin88]

Just setting up a 90 gallon tank, looking at RO/DI units for topping up and water changes, don't think I need a large unit but have a question about water pressure. Our water pressure is low, probably about 35-40 and most of the units I see are rated at 50 gph and 77 degrees. What will be the result of the low pressure, will the unit still work but with a much lower output, more waste? If I have to add a pump to increase pressure, this complicates and greatly increases the price of a unit so can probably buy a lot of water at the LFS for the price of a home unit?

Second question, what GPD rating would you suggest for a 90 gallon tank with a sump?

Thanks in advance, hope to learn a lot on this site.

Dave Martin

[Mr. Tang]

Correct me if I'm wrong but I believe that the more pressure you have the better the RO/DI filters the water. So with low water pressure lower quailty water. Trust me, in the long run you will spend more money buying water at the LFS!

[glampka]

Check out Products and answers for your water treatment needs. - they have a number of units. They know their stuff & have great customer service.

[davemartin88]

Originally Posted by Mr. Tang

Correct me if I'm wrong but I believe that the more pressure you have the better the RO/DI filters the water. So with low water pressure lower quailty water. Trust me, in the long run you will spend more money buying water at the LFS!

Thanks for the reply, I'm thinking that we will want to get a unit but it seems to me that with low pressure, the water that gets through it would be of good quality, but the volume would be low. Will check out the source in the other note to learn a bit more- just concerned about having to add pumps, etc. and greatly increasing the up front costs. Thanks again.

[gimmito]

Have you considered a cold sterile filter system ? Checkout my review over at

[davemartin88]

That link just takes me to another forum and not to anything specific?

[reefnoob1991]

You don't really have to worry about getting anything big and fancy with a 90 gallon...my 75 only evaps on metal halide lighting and an open top at the most 1 gallon per day, so who needs a 250 expensive GPD system when at the most in a week I only need up to about 10 gallons?

[renoreefer]

You may only need 10gal of r/0 water for top off but what about water changes????

I have a unit from WaterGeneral.com that I bought on Ebay and this unit has 6 stages
which includes 2 D/I chambers, under perfect conditions this unit should make 100gal
per day I'm on a well and not the best water and I can make 60gal in 72hrs which is
plenty for bi weekly water changes and top off for my 100gal system. If you want near perfect water quality for you sea creatures R/O D/I is the only way to go!!!

[davemartin88]

Originally Posted by renoreefer

You may only need 10gal of r/0 water for top off but what about water changes????

Went ahead and ordered a unit this morning and will add a pump if the low water pressure is an issue. We're planning on doing 20-25% water changes biweekly so figure that is 50 gallons a month minimum plus evaporation of 7-10 gallons per week. I like the idea of having the water available and not having to lug gallon jugs around.

Thanks to all who responded, hopefully the install will be as easy as it sounds.

[renoreefer]

Installs are easy just read instructions, I always have at least 30gals of salt water made up at all times with a heater and powerhead W/ air for areation just in case of a emergency water change!!!!!

I have way too much time and money invested in my system!!!!!!!!!!!!
BETTER SAFE THAT SORRY!!!!!!!!!!

[reefnoob1991]

Mine can make 4 gallons an hour although it's rated for 75 GPD...so thats really like 96 GPD. What I was trying to say was even with a large system there isn't much difference from a 75 GPD to a 220 GPD because unless God strikes you down and evaps 1/2 your tank you can just fill a bucket with some extra water in about an hour and keep it for when you need

[gimmito]

I noticed my reply got edited for some reason. Checkout Poly-Bio-Marine for more information on cold sterile filter systems.

[firefighter4567]

if u end up needing the booster pump get an aquatec 8800 i just bought one cause our water preasure died over this fall and it went from havin around a 30tds reading coming out of the filter b4 the DI to a 2 avg and as low as 0 most of the time. i couldnt believe it. and it boosted output greatly cutting down on waste water some. im still doing research if it would be a good idea to also add a perminate pump to the setup. heres some pics of my setup

firefighter4567/Fish Pics - Photobucket - Video and Image Hosting