RO/DI Question

[Lemeshianos]

I received my RO/DI unit yesterday. I connected it to the water supply and let it run for 3 hours(to get the solution that is used to keep it from freezing or developing bacteria out of the system).
I disconnected the DI part(2 DI parts because I didn't want to waste the resin for water that I would discard(don't worry, I'll water the plants with it).

Now my tap water TDS is 200 ppm.
The clean water reading is 45 ppm and the waste water is 300.
I checked the discard ratio and it is 1:4 or 1:5 somewhere around there.

Does this sound ok? 45ppm on the clean water?(without the DI's)
The membrane is rated to be 98% so my math tell me that it should show around 4ppm.

[Randy Holmes-Farley]

What brand?

The exact ratio depends both on the membrane and what is in the water, but yours seems fairly poor to me. Mine takes 90-100 ppm TDS tap down to about 5 ppm TDS out of the RO. :)

[Lemeshianos]

well the instructions say that it might show some elevated tds initially until the dust from the activated carbon prefilter gets completely out of the system. However I know the brand is one of the cheap ones. I will probably upgrade after a year when I'll turn the FOWLR tank to a reef.

[Mike31154]

See if you can get hold of another TDS meter (borrow?) to validate the readings you are getting with yours. I have both a handheld and an inline Dual TDS meter. A recent check of my source water TDS had the handeld reading just under 220 while both probes on the inline meter yielded a reading closer to 200.

As you can see by the above figures, my source water TDS is similar to yours and my 75 gpd RO membrane is able to get that down to 1 TDS within 5 minutes of starting the system up. At 45 TDS after your RO stage, you are going to be burning through DI media fairly quickly. You might consider trying a better quality membrane sooner rather than later. They're not that difficult to replace and you won't have to get a completely new system.

[Flipper62]

I have the dual TDS meters on my RO/DI system. 1 meter is after the filters / before the DI unit. The 2nd is the final water TDS reading.

I only use it as a guide to how the filters are doing. Watching when its getting time to change them out.

However.....after I make the water, I use a COM-100 portable TDS meter to test the water.

[PRDubois]

Is this one of those ebay jobs?

My TDS has been 0 comming out since I recieved the unit

[Lemeshianos]

I have run it again yesterday. It dropped down to 12 ppm(without using the DI yet).

Do you think it's decent?
I haven't made water for the tank yet, so I didn't use the DI's since I didn't want to waste them before setting up the tank.
Yeah it's one of those ebay RO/DI's. It's from purewaterclub and I find it really good actually(well except maybe for the membrane that I was expecting to be a cheap one). After all its the actual filters that make the difference, not the housing so I figure for a FO tank I would get a decent TDS reading and I can shell out for a good membrane when I slowly decide to build a reef tank.

Do you think I should hook up the DI's when I'll start making water or save it for when I build a reef?

[PRDubois]

Much better. When you put the DI on it will probally be 0

[Lemeshianos]

cool. thanks!
Also just wanted to ask, what flow in the tank is needed to keep a couple of ocellaris?
I've got very little flow at the moment and at the moment I can't spend big at the moment.(I live in Cyprus so everything I buy for costs me double to get is shipped here)

So I want to check what flow will be decent for ocellaris, just to know if I can start with a pair or to wait until I save enough for all the equipment.

[PRDubois]

You do not need that much for fish. Just a couple of powerheads should do. Do not have a glass top and point one of the powerheads towards the surface to get the gas exchange. Water surface should ripple a little.

[Lemeshianos]

Yes but what should I be looking at in terms of GPH? (tank holds about 75-80 gallons)

As for the gas exchange I have a trickle filter(pump produces air bubbles that agitate the surface) that I will keep until I get enough rock to remove it. So far I've got about the half of the rock I need but it's dead rock.

But no powerheads. I plan on getting two Hyror Korallia 3 in the future.
Will two small cheap pumps do the job? Cause if I have to get something stronger I'll probably just wait a few months longer.