What RODI for a low GPD need?

BOSLawGuy

New member
I will be setting up a holding tank for my RODI water, so don't need a system that does 100 GPD.

My whole system will be ~285-310 gallons, and my spare holding RODI tank about 50-75 gallons so.

Any suggestions? I was hoping that being able to go to a lower GPD means cost savings?
 

thegrun

Team RC
A 75 gallons per day system would work. Check out Bulk Reef Supply, they have several units to choose from. IMHO you should go with a system that includes duel TDS meter, oil filled pressure guage, and a RO flush valve no matter where you but it at. If your house water pressure is 40 PSI or less you will also nee a booster pump.
 

BOSLawGuy

New member
The RODI will be off the main water to the house, in the basement....
Why do I need a 75GPD system when I will have such a large holding tank?
 

thegrun

Team RC
Most of the commonly available filters are set up for 75 GPH systems and I doubt there is much of a price break for a lower GPH system which are not common.
 

E Rosewater

New member
The bulk reef supply upgrade kit to go from 75 to 150 gallons cuts your waste in half. So if you're worried about water waste or water bill that would be the best route. Not only that but but it decreases the amount of water through the pre-filters so you'll have a cost saving there.
 

James77

Team RC
The bulk reef supply upgrade kit to go from 75 to 150 gallons cuts your waste in half. So if you're worried about water waste or water bill that would be the best route. Not only that but but it decreases the amount of water through the pre-filters so you'll have a cost saving there.

They do that by piggybacking 2 membranes and still using the 75 gpd flow restrictor. Waste water is really flush water, the membranes rely on that to operate properly. I did the BRS upgrade to 2 membranes, which doubled the output and halved the "waste", but I soon had fouled membranes.

Here is article on RODI:
http://reefkeeping.com/issues/2005-05/rhf/
 

Fizz71

FragSwapper
75gph units tend to have really good rejection rates and there aren't too many units less than 75pgh that don't sacrifice something (like a pre-filter or two). Holding tank or not 75gph isn't overkill. I'm not sure how you're calculating the cost saving but no matter what speed it's rated at if it's cost savings you're looking for you have to look at 2 things.

#1. How many gallons it produces per gallons wasted? The more it wastes, the sooner your sediment and carbon blocks will wear out and the more city water you have to buy if you're on city water.
#2. What is the rejection rate? The lower the rejection rate the faster your DI is going to burn out to make up for what the membrane didn't pull out.

So whether it makes 75GPD or 300GPD if the rejection rates and waster water rates are the same the cost is really the same. Especially if you compare 2 similar 5 stage RO/DIs...the only difference is the membrane and a little piece of rubber that controls the back pressure into the RO membrane.

I have about the same amount of water as you and I'm running a 75gpd unit on a 55g drum with a second 55g W/C drum ready to go. I would not go less than 75GPD, as it stands now if I do a 55g water change when the top-off is low I have to run it more than a day to refill.

I don't like leaving my RO running because it's the only way Murphy could sneak in since the top-off is automatic...so if something happens and the top-off sticks I have it set up that no more than 25g of RO/DI could possibly get added to my system which would drop the tank to no less then 1.023. If the RO were left on at all times it would just continue to drive my salinity down until I noticed things dying.

At 75GPD when the top-off gets low I turn in on at night and back off in the morning. I will eventually get it back on a timer so it only runs every few days for a few hours.

If I were in your shoes (and I was 2 years ago) I'd go for a 5 stage 75GPD and add whatever bells and whistle you think you need. I have a dual TDS meter and a pressure gauge. I also have an auto-shutoff which doesn't work because my water pressure is too much for it. I bought my unit from BRS.
 

BOSLawGuy

New member
Fizz,

Thank you! I was looking at BRS myself.
As for the shut off, I thought you use a tank leveler to do that? I'm confused as to why water pressure would come into play here?
 

Fizz71

FragSwapper
There's a float that stops any additional RO from going into my storage tank which is then supposed to build up enough back pressure in the unit that it trips an auto-shutoff valve to stop the water from coming in to the unit. My pressure is too high and the auto-shuttoff doesn't work so the RO unit continues to run. BRS even sent me a replacement in case it was bad, but it wasn't the unit...it was my house. I hooked my RO up to my fridge's water supply line just for sh*ts and giggles and it worked fine.

Since there is a float valve on the product (RO) line it doesn't actually fill the drum any more or cause a flood, but it does run out of the waste water line until I shut it off by hand. Burning out my carbon and sediment blocks.

It's all my fault....I have EXTREMELY high pressure and made the mistake of tapping for the RO unit before the home's pressure reducer instead of after it. And pressure greatly affects an RO because the more pressure, the faster it produces. If you have low pressure your 75GPD unit may only produce 40 or 50 GPD..that happened to my on my LAST house with a well. So this time I said...I'LL SHOW YOU...and tapped right were the water enters the basement to get the most pressure I could from the city. [hand slaps head] Oh well.

Anyway. I have a float in my drum to stop the RO and a float to my sump to control top-off so technically my RO has a direct line to my tank...a very dangerous thing if you don't have checks in place. In my case the check was SUPPOSE to be an electronic system that only allowed the water to feed the RO a few hours every few days but the solenoids I bought couldn't handle the d*mn pressure either. So for now I just turn the feed line on once every week or so (depending on how fast I deplete the top-off) by hand. So for that stretch of time my RO is on it won't flood anything because of the floats, but if I should have a leak or a sump pump go ape-sh*t and spray water out of my sump, the top-off will try to replace it and then the RO will CONTINUE to replace it and plummet my salinity.

I tried to make the system as autonomous as I could. Once I get the new water timer in place and stable (it's built, just not running yet) my tank could go for months without me needing to touch it. All I need to do is clean the skimmer once in a while and do my W/C which is done with pumps and switches. This is all in the basement out of sight and out of mind. Of course I have to feed the fish and I'm constantly battling coraline on my acrylic, but I've built a pretty hands-off system in terms of daily crap.
 
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