Tap water vs RO vs carbon filter

Definitely basing my logic in reducing costs. My first grow I bought all the magic potions and used RO water. Went great but I didn’t like how much it cost. My goal is to grow great weed on the cheap.

If you are able to grow a thriving garden outside using tap water then you shouldn’t be too concerned. Now, if lead is contaminating the water you definitely don’t want to use it. Your cannabis will accumulate it and you will consume it.

this is assuming you’re growing in soil. If you’re doing hydro then I would assume RO is better.

OverCloudz said:

Can I ask you your experience with feedings your plants RO water?
I’m still debating RO vs a single carbon filter.
The reason for going with a carbon filter vs RO is because it’s cheaper, faster to fill up, no wasted water, it keeps some of the needed minerals and still seem to be doing a good job at lowering the ppm (especially chlorine). RO seem to be more complicated, I’ve dig lots of messages on forums and many RO users seemed unhappy and switched to carbon filter. It needs more care, seems like it’s not so good to use with clones/seedlings and most people say it’s better to mix like 25% tap to get some of the wanted minerals otherwise there’s lots of probable deficiency problems. It always sounds more complicated than just adding cal/mag and you’re good to go.
Seems like 50% of people who used it swear by it and 50% had problems and regret buying a RO filter.

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Carbon filters only remove odors and taste but not any minerals so won't lower the ppm or reduce heavy metal contamination like lead, cadmium etc.

The only thing 'complicated' about using RO water for plants is you might need to add a dash of calmag once in a while tho most nutrients and soils have enough of both but a ton of people seem to think calmag is the cure for everything that can go wrong with plants.

I have used nothing but RO or distilled water for over 20 years and that's all we drink or use for cooking and coffee making here. A filter to add minerals like calcium, magnesium, potassium and raise the pH of your drinking water can be added on but cost almost as much as small 3 or 4 stage RO unit.

I would not drink the tap water in town that passes as potable water. I've got the water analysis report from them and it's quite high in sodium, iron, alkalinity and a few others and close to 300ppm. The water where I grew up next to Vancouver, BC and we used their water supply was at one time rated the best tap water in north america and could still be for all I know. I'd use that on my plants no problem.

Using pure water means something else is wrong if my plants are doing poorly ans saves a lot of time wondering if the water is the source of the problem

All city/town water supply lines become coated with a bio-film inside which keeps the water from actually contacting the surface of the pipes that may be cast iron or even lead in older systems. What happened in Flint, Michigan was they switched water sources to one that was slightly acidic which stripped the bio-film off the insides of the pipes. The bio-film itself had contamination trapped in it for a surge of heavy metals then the acidic water began leaching lead out of the old pipes and poisoning everyone that drank it or used it for cooking or even bathing. Very bad for everyone but especially for growing children.

When a water source is below pH 7 usually calcium carbonate or something like it is added to the water to raise the pH over 7 to protect the infrastructure the water will come into contact with like pipes and pumps.

I'm sure your plants will be fine with your water filtered or not. Bacteria that could harm a human won't hurt plants. Think of what they are exposed to in the wild.

I bet it's galvanized pipes; does your water ever come out "rust" colored after heavy rains, etc? Huge chance it's that. Should be "fine" for plants, but since we're often talking about medicianl plants it's always a good idea to give them the best water you can access. I'd say carbon filtration of your tap water should be more than adequate.

Roger A. Shrubber said:

that actually works, carbon filters do eliminate about 98% of lead in water....and they're cheaper than ro filters, most places.

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Carbon alone won't take out much heavy metals. Specially activated carbon filters can remove most but should say that on the packaging. Things like Brita filters that have carbon and ion exchange beads in them can remove over 98% of heavy metals like lead. They won't remove a lot of things or reduce ppm tho. Brita worked great back in BC for our deep well water but the town water up here still tasted like crap even with a new filter.

RO is for sure to me the best sol'n but a lot more money to get going. Kinda like LED lights. I did the math compared to the cost of buying my RO for $3.49/5gal and it will take about 6 months to pay back the $550 all the bits and pieces cost me. Still a lot cheaper than running the Polar Bear distiller downstairs that takes about 20hrs to make 10USG using a 1500W heating element that needs replacing. Cleaning that up and putting a new $100 element in then selling it. Refurbished in the same model are going for $1800 so should be able to get a grand for it. Over 3G new.

If cost is the only reason to go with a carbon filter vs RO, I found this unit, 100$usd, 100GPD, 6 filters. I don't know if it's good enough though. I'm changing my mind every seconds with this decision for some reason, can't make up my mind

OverCloudz said:

If cost is the only reason to go with a carbon filter vs RO, I found this unit, 100$usd, 100GPD, 6 filters. I don't know if it's good enough though. I'm changing my mind every seconds with this decision for some reason, can't make up my mind
View attachment 5262879

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I'd grab that up and something I should of got but I like a project so building mine from scratch. That looks like it has the mineral filter to add back but that raises pH a bunch which is healthy for drinking but not so much for the plants. I'd rig a take-off to get the plant's water before that filter like I'm doing with mine. And use that water for a coffee maker too to keep it from crusting up inside.

That tap unit would be a PITA so have a valve or something to stick the end of the line into a water jug and let it go until full. I got the little tube cutter and have many connections to make so praying for no leaks.

Adding a small UV filter will be another $100 but if you're on city water that's fit to drink not really needed.

OldMedUser said:

I'd grab that up and something I should of got but I like a project so building mine from scratch. That looks like it has the mineral filter to add back but that raises pH a bunch which is healthy for drinking but not so much for the plants. I'd rig a take-off to get the plant's water before that filter like I'm doing with mine. And use that water for a coffee maker too to keep it from crusting up inside.

That tap unit would be a PITA so have a valve or something to stick the end of the line into a water jug and let it go until full. I got the little tube cutter and have many connections to make so praying for no leaks.

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Here is a picture of what you are talking about. Are you talking about the post carbon filter? So if i understand correctly, this will bring back minerals into the water like calcium/magnesium, bump the ppm and PH. Why not just throw some ph down afterwards? Isn't it a good thing to have?

OverCloudz said:

Here is a picture of what you are talking about. Are you talking about the post carbon filter? So if i understand correctly, this will bring back minerals into the water like calcium/magnesium, bump the ppm and PH. Why not just throw some ph down afterwards? Isn't it a good thing to have?
View attachment 5262890

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You could do that too but then more dicking around playing with pH. RO water is neutral so will not affect the pH in your pots one way or another. I use pH Perfect AN nutes unless doing organics in HP so just mix in my nutes and feed the plants. Never even think about pH.

OP: is collecting rainwater feasible?

rain water would be too complicated

After more research, this is what I understand from this debate (can you guys tell me if there is something false)

First, everyone should test their water and see what filter options to get. But most of us won't do that. Also everyone should at least have a carbon filter.

- 300+ ppm tap water should go with RO automatically.
- 300- ppm tap water should at least get a carbon filter to eliminate chlorine.
- When using RO always add cal/mag to your water so it has a total of 200ppm
- On forums 50% of people have problems using RO and they regret getting it. They have new deficiencies probably because of missing nutrients from the tap water. Now I have to guess if they added cal/mag everytime and I don't have the answer to that. This is the biggest missing information here. I would really like to have the opinion of someone who has RO, added right amount of cal/mag but still had problems vs when he was using tap.
- 50% of people swear by RO, The 2 biggest reasons are: 1. They know exactly how much cal/mag will be in their water by adding it. 2. They know they don't have unwanted solids in their water. Without RO, we still have to add cal/mag when using coco so we might over feed it and have problems.

Let me know if i said something incorrect.

Good nutes should have all the macro and micro nutrients the plants need. I've done about 50 DWC grows since '01 and never had calmag for the first 30 or so all using RO water and AN 3-part. Some Epsom Salts in flower and they were fine.

I do use calmag now but very little as I'm growing in pots of HP using mostly organics so they should have plenty of everything. Lots of 2 types of lime in HP so lots of Ca.

This really isn't rocket science.

OverCloudz said:

After more research, this is what I understand from this debate (can you guys tell me if there is something false)

First, everyone should test their water and see what filter options to get. But most of us won't do that. Also everyone should at least have a carbon filter.

- 300+ ppm tap water should go with RO automatically.
- 300- ppm tap water should at least get a carbon filter to eliminate chlorine.
- When using RO always add cal/mag to your water so it has a total of 200ppm
- On forums 50% of people have problems using RO and they regret getting it. They have new deficiencies probably because of missing nutrients from the tap water. Now I have to guess if they added cal/mag everytime and I don't have the answer to that. This is the biggest missing information here. I would really like to have the opinion of someone who has RO, added right amount of cal/mag but still had problems vs when he was using tap.
- 50% of people swear by RO, The 2 biggest reasons are: 1. They know exactly how much cal/mag will be in their water by adding it. 2. They know they don't have unwanted solids in their water. Without RO, we still have to add cal/mag when using coco so we might over feed it and have problems.

Let me know if i said something incorrect.

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It all depends on what your grow media is. Soil vs coco vs rockwool vs dwc are all going to be different. In soil grows you will rarely need RO. In hydro grown you will most likely want RO, so that you are beginning from a "clean canvas" in terms of your nute profile. Many quality fertilizers will not require adding CalMag to your feed, even when using RO.