Best way to collect runoff to test PH and TDS?

Once I transplant my seedling I will have a 5 gallon smart pot sitting on a 16" plastic saucer. Should I use something like a syringe or a turkey baster to suck up some of the runoff so I can add enough to a glass to be able to put my probes in?

Will a smart pot absorb the runoff or will I have to dump the saucer each time I water?

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I use a turkey baster, and put into plastic cups, then measure.

Plants are in big plastic totes, spaced from the bottom with pvc pipes. I can get 2-3 gallons in there before it hits the bottom of the pot. Then I either suck up the water with a wet vac, or lift plant out, dump water, and replace the plant.

You don’t want the plant to re absorb the runoff, it’s waste and full of salts. You wouldn’t drink your own pee would you?

Keep in mind, if you use a big tote like I do, things Accumulate in the bottom, (foliar sprays or old unremoved runoff ) so if you don’t keep it clean the readings can be off.


Yep, syringe or turkey baster works, but you’re not going to want to water a small plant/seedling in a 5 gal enough to have any runoff, as that would really over water it and cause your plant problems. If we’re talking about a fabric pot, it will absorb the standing water, whether that is good or not can be up for debate.


I agree with not watering seedlings to runoff. If that’s what you plan to do, run test through the media before you do the transplant. Then allow to dry out some before doing transplant. or do a slurry test instead.


And I fail to see the point of doing a runoff test on brand new soil after a transplant. If you get the right soil, the ph is going to be fine.


I should have been more specific. I won’t be watering the seedling to runoff. I am thinking ahead to when the plant is big enough for nutrients. This is a single plant, closet grow so I am trying to figure out how to do this without making too much of a mess. I will probably have to set a tarp down over the carpet so that I can take the smart pot out of the saucer and dump the saucer.

I like the idea of the pvc pipes under the pot to keep it out of the runoff. Is there anything else that is commonly put under the pot besides pvc?

Is it necessary for the fabric pots to have air circulation underneath them?

@Not2SureYet can you show him how you have yours up over your pans?

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I’ve seen metal grates/shelving used too. I like the pvc because it’s cheap, easily replaceable, and inert so no worries about retaining moisture or fostering fungus gnats.

Raising the pot for more airflow is an added bonus


Maybe if I was on a deserted island. LOL

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I use these to keep my fabric pots out of the water. Buy them at a hydro shop, much cheaper, like $4 each.


Just like your plant. If it was desperate for hydration, runoff would be better than nothing. I still wouldn’t make a habit of it.

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If I was hanging out with Bear Grylls, I would.


From what I understand, drinking urine is fine the first time, but after that it becomes toxic as you’re just recycling all your waste.

Just in case you find yourself on a deserted island with bear grylls :grin:

Of course he’ll have a helicopter at the ready, to bring him to his hotel, while you starve.


I really like this idea. Then I can lift the smart pot by the gro pro and not have to worry about disturbing the roots or handles breaking. I can just get another large saucer and switch back and forth as they need to be emptied. Thanks.


Fox farms is all over the place, brand new right out of the bag. Definitely not much consistency bag to bag. I don’t test it either, just hit it with dolomite lime because I expect it to suck. I wouldn’t call it a great soil though, but it easy to get and not expensive.

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I’m fairly happy with ffof, it does a great job for a month. I have tested runoff right out of the bag. Wow, the ppms are off the hook. Usually 2500-3500.

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Not suggesting it won’t work. But I don’t believe they have great mixing process. If you grow in smaller pots to where you’re filling multiple pots out of same bag can be a pita. Or if you have a lot of plants and several bags the same.

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Here are a few ideas that are almost free.
My first and still use as a back up is an old refrigeration rack on some old tin cans

Next. got on craigslist and found a twin bed with an aluminum frame. Cut up it worked perfect for 2 plants.

Next I added wheels to it to make it easier to move around

I took a section and cut the tubing down so I could make some individual racks too. @Myfriendis410
Cut the wood and drilled the holes. I can completely dissemble it for flat storage if I need. I added some wood on the bottom for the trays to sit on. And added wheels to these as well. They are great for when I want to do one plant under a 2x4 scrog. or if I want to separate the plants a little. The wheels are super cheap.

I probably have 35.00 in the 2 40" racks, one 30" rack and three of the single racks. :grin:
I hope this may give you an idea or 2


Great setup! Love the bamboo scrog!

I actually have a question on the same topic. I fed at 6.5pH and my run off from FF HF was 7.2pH. Should I adjust the start pH to compensate?

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