RO/DI question

bowhunter103 · 03/21/2014, 09:29 AM

I have a 75gpd RO/DI unit. I also have a TDS monitor hooked up so I can monitor the incoming TDS to the unit and the exiting TDS coming out of the DI. I am consistently running between 328 to 347 TDS incoming and 1 TDS after the DI. Is this TDS number acceptable to keep green hair algae from growing when I add water to my tank and when doing water changes? Do I need to install an additional DI unit to clean up the remaining TDS?

drew2007 · 03/21/2014, 09:39 AM

Quote:

Originally Posted by bowhunter103

I have a 75gpd RO/DI unit. I also have a TDS monitor hooked up so I can monitor the incoming TDS to the unit and the exiting TDS coming out of the DI. I am consistently running between 328 to 347 TDS incoming and 1 TDS after the DI. Is this TDS number acceptable to keep green hair algae from growing when I add water to my tank and when doing water changes? Do I need to install an additional DI unit to clean up the remaining TDS?

Your goal is 0 tds out from di but 1 tds from those input numbers is good. I don't think adding another di is gonna make a difference. With those high tds numbers coming in you will burn through di pretty quick. Have you ever had 0 tds? 1 tds isn't going to cause gha. Typically gha is due to nitrate and phosphate.

bowhunter103 · 03/21/2014, 09:53 AM

I have never seen 0 TDS. I have on rare occasion seen my incoming TDS at 280ish, but more often than not it is where I stated. I've been told that I can hold off changing my DI until my TDS get to about 3-4. I was afraid that I was introducing food to my GHA problem (See "Green Hair Algae Explosion") with a TDS at 1 and not 0.

Portsie · 03/21/2014, 10:40 AM

I think you should be shooting for 0. My tap water is about the same TDS as yours, but I get 0 after my di. Try checking the TDS before and after your RO membrane, it could be time for a new one. Or maybe you just need to replace the carbon and/or sediment. I definitely go through di somewhat quickly, but its worth it to me for 0 TDS. Even if its only 1, you have no idea of what that 1 is.

bowhunter103 · 03/21/2014, 11:00 AM

All of my cartridges are less than two months old. The sediment cartridge has just started to get a red tint (iron removal I'd guess). I can't imagine that my cartridges are exhausted already! I've only done 4, maybe 5 20% (40 gal) water changes on these cartridges.

Portsie · 03/21/2014, 12:27 PM

I probably change my sediment filter every 2 or 3 months, and replace my di resin around the same time. My unit came with a pretty small di canister though, and I just replaced it with a standard canister with the refillable di insert.

03/21/2014, 09:29 AM	#1
bowhunter103 Registered Member Join Date: Mar 2014 Location: South Dakota Posts: 11	RO/DI question I have a 75gpd RO/DI unit. I also have a TDS monitor hooked up so I can monitor the incoming TDS to the unit and the exiting TDS coming out of the DI. I am consistently running between 328 to 347 TDS incoming and 1 TDS after the DI. Is this TDS number acceptable to keep green hair algae from growing when I add water to my tank and when doing water changes? Do I need to install an additional DI unit to clean up the remaining TDS?

03/21/2014, 10:40 AM	#4
Portsie Registered Member Join Date: Jul 2012 Location: New Brunswick, Canada Posts: 741	I think you should be shooting for 0. My tap water is about the same TDS as yours, but I get 0 after my di. Try checking the TDS before and after your RO membrane, it could be time for a new one. Or maybe you just need to replace the carbon and/or sediment. I definitely go through di somewhat quickly, but its worth it to me for 0 TDS. Even if its only 1, you have no idea of what that 1 is. __________________ 90g corner overflow, 33g sump, Apex, Vertex IN-100, 2x MP-10w ES, 1X MP-40w, Tunze Osmolator, 60lbs Caribsea oolite, 85lbs live rock, 4x54w T5 with LED moonlights

03/21/2014, 12:27 PM	#6
Portsie Registered Member Join Date: Jul 2012 Location: New Brunswick, Canada Posts: 741	I probably change my sediment filter every 2 or 3 months, and replace my di resin around the same time. My unit came with a pretty small di canister though, and I just replaced it with a standard canister with the refillable di insert. __________________ 90g corner overflow, 33g sump, Apex, Vertex IN-100, 2x MP-10w ES, 1X MP-40w, Tunze Osmolator, 60lbs Caribsea oolite, 85lbs live rock, 4x54w T5 with LED moonlights

03/21/2014, 09:53 AM	#3
bowhunter103 Registered Member Join Date: Mar 2014 Location: South Dakota Posts: 11	I have never seen 0 TDS. I have on rare occasion seen my incoming TDS at 280ish, but more often than not it is where I stated. I've been told that I can hold off changing my DI until my TDS get to about 3-4. I was afraid that I was introducing food to my GHA problem (See "Green Hair Algae Explosion") with a TDS at 1 and not 0.

03/21/2014, 11:00 AM	#5
bowhunter103 Registered Member Join Date: Mar 2014 Location: South Dakota Posts: 11	All of my cartridges are less than two months old. The sediment cartridge has just started to get a red tint (iron removal I'd guess). I can't imagine that my cartridges are exhausted already! I've only done 4, maybe 5 20% (40 gal) water changes on these cartridges.