Green Intex pool - help!

[estepeste]

Hi all

My Intex above ground pool has turned green.
It has only been a couple of weeks, I'm hoping I can turn in back into a blue pool relatively quickly.

I have checked all the levels with my strip test kit, not as accurate as the fancy test kits, but it's all I have...
FCl: 15ish
Alk: 80ish
pH: 7.2 (i have adjusted it but apparently the reading won't be accurate if FCl is above 10.
CyA: 40ish

We have upgraded the filter from the Cartridge type, to a Sand filter yesterday.

Do I just keep all levels within acceptable range, and the FCl higher around 15 to eliminate the algae?
I'm not sure at what point the Vinyl liner will be a factor - don't want it ruined of course.

How long will it take to get rid of the green?
I've seen people getting their pools back to sparkling overnight - or is that not typically what happens?

Would Oxygen shock (non-chlorine shock) be a good idea, or would I achieve the same with just putting more granular Chlorine in (Safe-T-Chlor - 630gm's/kg available chlorine present as Sodium Dichloroisocyanurate.)

We have a fair amount of leaf debris, but now have a leaf skimmer to get most of the floaties.

We backwashed the filter this morning, plan to do it at least once a day.
The FCl levels don't appear to drop as fast now as it was doing a few days ago, hoping that means we are on the right track?
Any help much appreciated - our 3 boys are super keen to get back in the pool!
(Yesterday)
(Today)

 

[needsajet]

Welcome to TFP! Good to have you here

You have a few choices, one of which is a proper test kit as you mentioned. This thread describes how TFPC works: TFPC for Beginners and this link will point you to a kit that's available in New Zealand: Total Pool Water Testing Kit, Fresh Water Clear Choice Labs

Another option is to replace the water and follow this system: Pool School - Guide for Seasonal/Temporary Pools

Either way, there will be people here who can help walk you through it.

 

[estepeste]

Thank you. I will look into the kits and the other information, and look forward to more replies about hoping making it happen with what I've got on hand if possible

 

[Texas Splash]

estepeste, welcome to TFP! I had that exact pool at one time. The fact you upgraded to a new sand filter should help quite a bit, but it will not change the water from green to clear. That is 100% a chemical issue. As needsajet mentioned, it all starts with the right test kit. Those test strips are horrible. Not your fault, it's just a fact they are way off. Definitely do not add anything to the water except some "regular" bleach (non-scented) to the water each day - maybe a half gallon per day until you get the proper test kit. I wouldn't add anymore pool store products (bags of shock, etc). If you do decide to drain all the water, then it won't be long before it turns green again without knowing the accurate test numbers. The right test kit will save you a lot of headache, time, and wasted chemicals, so do what you can to get one as soon as possible.

We'll help you from there. Very nice to have you with us on the forum.

 

[needsajet]

Avoid any more dichlor because your stabiliser level may already be too high. Dichlor adds both FC and stabiliser (aka CYA, aka cyanuric acid). Stabiliser protects FC from sunlight, but when it gets too high, it stops the FC from doing its work. The test strip test for CYA is unreliable, along with the other numbers the test strips suggest.

We use algae as an indicator that sanitation is or may be inadequate, and the safest, most effective, and easy way to kill both algae and bacteria is chlorine. You can chlorinate the pool with liquid chlorine (12.5% sodium hypochlorite from Bunnings pool section, $13 for 15 litres plus a one-time $10 deposit). Liquid chlorine does not add any CYA, so you won't run into the problem of getting the water over-stabilised.

Oxygen shock is usually potassium monopersulphate (MPS) and is not likely to help in your situation.

 

[needsajet]

I absolutely agree that the test kit is your best way to go.

It's also reasonable to suggest that draining and cleaning the pool might get you swimming faster. Following the seasonal pool method will give you many weeks of good swimming and clear water. It all depends how you'd prefer to spend your money, how soon you want to be swimming, and how much of a swimming season you have left. There's a very good chance that your CYA is too high and you'll be partially draining and refilling before chlorine will work to clear the water. Pat makes an important point that draining will not get rid of every algae cell, so on the initial fill you have to be sure that you kill off the stragglers with the initial chlorination.

Getting a test kit and doing a SLAM will take around a week, and probably more like 10 days if life gets in the way. The drain/refill and following the seasonal pool method should have your kids in the water by the end of the week as long as the pool gets some sun to warm up the water a bit

Either way, you'll probably want the test kit for next year, so that's worth factoring in as well.

I haven't been able to find bleach that's cheaper than chlorinating liquid from Bunnings. There's some kiwis here that would know if it's the same in NZ as it is here in Aus.

The only thing I would buy from a pool store is the standard 4 in 1 drop-based test kit, which would allow you to use the seasonal pool method. It's quite reliable for pH and TA, and marginally adequate for FC between 1 and 4 ppm. You can run your pool at a calculated 30 ppm CYA and 2-4 ppm FC for quite a while.
AussieGold 4 in 1 Test Kit for Swimming Pools (Chlorine, pH, Acid, Alkalinity)

But again, it's better use of money to put that $35 towards the $122 ClearChoiceLabs kit.

Happy to help out either way, as are many of us cause we've all been there, just where you are now All our recommendations will be based on effective methods that cost the least money. One of the great things about this forum is that there's experts who will correct anything that's wrong or misleading.

 

[estepeste]

Thanks. I have decided to empty the pool and start again.
What kind of FCl level should i have the initial water at to get the straggler algae cells eliminated? 10? or more?

Will try to be much better about keeping the pool chemical levels at the right levels from the start this time....

I absolutely agree that the test kit is your best way to go.

It's also reasonable to suggest that draining and cleaning the pool might get you swimming faster. Following the seasonal pool method will give you many weeks of good swimming and clear water. It all depends how you'd prefer to spend your money, how soon you want to be swimming, and how much of a swimming season you have left. There's a very good chance that your CYA is too high and you'll be partially draining and refilling before chlorine will work to clear the water. Pat makes an important point that draining will not get rid of every algae cell, so on the initial fill you have to be sure that you kill off the stragglers with the initial chlorination.

Getting a test kit and doing a SLAM will take around a week, and probably more like 10 days if life gets in the way. The drain/refill and following the seasonal pool method should have your kids in the water by the end of the week as long as the pool gets some sun to warm up the water a bit

Either way, you'll probably want the test kit for next year, so that's worth factoring in as well.

I haven't been able to find bleach that's cheaper than chlorinating liquid from Bunnings. There's some kiwis here that would know if it's the same in NZ as it is here in Aus.

The only thing I would buy from a pool store is the standard 4 in 1 drop-based test kit, which would allow you to use the seasonal pool method. It's quite reliable for pH and TA, and marginally adequate for FC between 1 and 4 ppm. You can run your pool at a calculated 30 ppm CYA and 2-4 ppm FC for quite a while.
AussieGold 4 in 1 Test Kit for Swimming Pools (Chlorine, pH, Acid, Alkalinity)

But again, it's better use of money to put that $35 towards the $122 ClearChoiceLabs kit.

Happy to help out either way, as are many of us cause we've all been there, just where you are now All our recommendations will be based on effective methods that cost the least money. One of the great things about this forum is that there's experts who will correct anything that's wrong or misleading.

 

[needsajet]

Let's start with a good pool volume estimate. What is the depth of the water? And the diameter of the pool?

Good instincts! If it were mine, I'd start it at 30 ppm CYA and do the initial fill at 12 ppm FC. It will fall while the water warms up.

Are there any green streaks or heavy spots on the vinyl? Mopping with diluted chlorine might be helpful either way.

 

[estepeste]

Hi needsajet it's a 15 x 48 Intex, so the estimated volume is 4500 gallons (or 17,000 litres).
Diameter 4.5 metres x 1.1 (water level) metric.
Not too many streaks or heavy spots on the vinyl, but i have scrubbed with brush today just to be sure.
Shall i just put the dichlor in, or do a douse with the calcium hypochlorite for the start?
I was concerned the hypochlorite would lower the pH too much...?

 

[needsajet]

Ideally, all you would use for FC (free chlorine) is chlorinating liquid, and you would use pure stabiliser to get the CYA level correct. I recommend we stick to the system shown in the seasonal pool link. Anything we do to use up chemicals is deviating from that.

Take a look at PoolMath, that's what is used for figuring out chem additions. I entered 17,000 litres at the top (don't include the comma)

So, going our own way to use up chemicals, and assuming you have 1 kilo of dichlor, here's a plan. Do you have more or less than a kilo?

You need to get CYA into the water. 12 ppm FC using dichlor is 370 grams, which also adds 11 ppm CYA, which is a start on the CYA. This is fine, but it's not OK for swimming. That's why we prefer to just buy stabiliser and get the CYA correct right from the start, and then use chlorinating liquid.

After the dichlor is well mixed in, you'll need to check pH. If it's between 7.2 and 7.8, all good.

Then you'll let the FC fall to 4 ppm FC before swimming (you'll need the test kit I linked). That should take a day or two as the water warms up.

After another day, FC should be down to 2, and then you can start adding dichlor to replace the FC that's lost, and your CYA will gradually build up. If it works out from PoolMath that you can add 100 g of dichlor each time, you can do this 7 times and then CYA will be right around 30 ppm.

How much CalHypo do you have?